Optical elements for beam-shaping and illumination

ABSTRACT

An example device may include a light source, an optical element, and, optionally, an encapsulant layer. A light beam generated by the light source may be received by the optical element and redirected towards an illumination target, such as an eye of a user. The optical element may include a material, for example, with a refractive index of at least approximately 2 at a wavelength of the light beam. The light source may be a semiconductor light source, such as a light-emitting diode or a laser. The optical element may be supported by an emissive surface of the light source. Refraction at an exit surface of the optical element, and/or within a metamaterial layer, may advantageously modify the beam properties, for example, in relation to illuminating a target. In some examples, the light source and optical element may be integrated into a monolithic light source module.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/802,995, filed 8 Feb. 2019, and U.S. Provisional Application No.62/841,728, filed 1 May 2019, the disclosures of each of which areincorporated, in their entirety, by this reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate a number of exemplary embodimentsand are a part of the specification. Together with the followingdescription, these drawings demonstrate and explain various principlesof the present disclosure.

FIG. 1 is a schematic of a device including a light source and anoptical element.

FIGS. 2A-2F illustrate optical elements with various exit surfaceconfigurations.

FIGS. 3A-3B qualitatively illustrate the illumination uniformity of atarget.

FIGS. 4A-4G illustrate fabrication of a light source integrated with anoptical element.

FIG. 5 shows an array-like arrangement of light sources and associatedoptical elements on a semiconductor wafer.

FIG. 6 illustrates fabrication of light sources and optical elements onseparate semiconductor wafers.

FIG. 7A shows a device including a light source, an optical element, andan encapsulant layer, and FIG. 7B qualitatively illustrates beamuniformity.

FIGS. 8A-8C and FIGS. 9A-9B show example devices including a lightsource and an optical element with a curved exit surface, andillumination of a target.

FIGS. 10A-10D further show illumination of a target using a deviceincluding a light source and an optical element with a curved exitsurface.

FIG. 11 illustrates a substrate supporting an arrangement of lightsources and associated optical elements.

FIG. 12 illustrates illumination of an eyebox using a plurality of lightsource/optical element combinations arranged at different radialdistances from the optical center of the lens.

FIGS. 13A-13B show an example device that includes a light source,optical element, and an encapsulant layer, and FIG. 13C shows a freeformexit surface of an optical element having properties that may, in someexamples, be at least approximately replicated by a metamaterial layerand a wedge element.

FIG. 14 shows beam shaping of a laser light source using an opticalelement that includes a metamaterial layer.

FIG. 15 shows an example arrangement of nanopillars on the surface of asubstrate.

FIG. 16 shows an array of nanopillars configured as a metamateriallayer.

FIG. 17 shows a randomized arrangement of nanopillars configured as ametamaterial layer.

FIG. 18 shows an example device including a metamaterial layer and anoptical element.

FIG. 19 shows an example phase profile for an example metamaterial layercombined with a wedge element.

FIGS. 20A and 20B show a generally periodic and randomized arrangementsof nanopillars, respectively, configured as metamaterial layers.

FIGS. 21A and 21B show light beam profiles for a wedge element alone,and for a wedge element combined with a metamaterial layer,respectively.

FIG. 22 shows an example method.

FIG. 23 shows an example control system that may be used in exemplarydevices according to some embodiments.

FIG. 24 is an illustration of exemplary augmented-reality glasses thatmay be used in connection with embodiments of this disclosure.

FIG. 25 is an illustration of an exemplary virtual-reality headset thatmay be used in connection with embodiments of this disclosure.

FIG. 26 an illustration of an exemplary device that incorporates aneye-tracking subsystem capable of tracking a user's eye(s).

FIGS. 27A-27B show more detailed illustrations of various aspects of theeye-tracking subsystem illustrated in FIG. 26.

Throughout the drawings, identical reference characters and descriptionsindicate similar, but not necessarily identical, elements. While theexemplary embodiments described herein are susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and are described in detailherein. However, the exemplary embodiments described herein are notintended to be limited to the particular forms disclosed. Rather, thepresent disclosure covers all modifications, equivalents, andalternatives falling within this disclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

A light source, such as a laser, may emit a light beam having variousproperties, such as beam direction and beam profile. As is described ingreater detail below, the present disclosure describes methods andapparatus for modifying light beam properties, for example, to improvethe illumination uniformity of a target.

Examples of the present disclosure include optical devices, such as adevice including an encapsulated optical element (e.g., an encapsulatedlens), and devices and methods related to modifying the properties of alight beam emitted by a light source. In some examples, a device mayinclude an optical element encapsulated by, adjacent, or substantiallyadjacent to, an optical medium. The optical element may have arefractive index greater than that of the optical medium (or surroundingencapsulant layer including the optical medium). The example opticaldevices described herein may also include one or more light sourcesand/or optical elements, such as optical elements used for beam-shapingand illumination, and/or devices, systems, and methods including opticalelements. In some examples, a device includes a light source, such as alaser, configured to emit a light beam. The light beam (which may moreconcisely be referred to as a beam) may have various beam properties,such as beam direction and beam profile. The examples described hereinmay include approaches to modifying one or more beam properties in amanner that may be useful for many applications, including eye-tracking.

Examples of the present disclosure may relate to example high refractiveindex optical elements that may be used for beam shaping and/or beamsteering of light beams from light sources, such as those used ineye-tracking systems. In some examples, the optical element and(optionally) the light source are embedded in an encapsulant layerhaving an intermediate refractive index. The encapsulant layer (whichmay also be referred to simply as an “encapsulant” for conciseness) may,for example, include an optical medium such as a generally transparentpolymer. In some examples, a high refractive index optical element mayinclude an optical medium (such as a semiconductor, or dielectricmaterial) having a refractive index greater than 1.5, in some examples,greater than 2, and in some examples, a refractive index ofapproximately 3 or greater. The encapsulant layer may include an opticalmedium, such as an optical polymer, having a refractive index that maybe less than that of the high refractive index optical element. Forexample, the encapsulant layer may have a refractive index of betweenapproximately 1.3 and approximately 1.8, such as approximately 1.5. Thehigh refractive index optical element may include a complex surfaceform, such as an anamorphic aspheric surface. In some examples, modelingshowed improved illumination uniformity of the eye, even for highprojection angles, for optical elements having an aspheric curved exitsurface. For example, a light beam from a light source may be directedtowards the center of the eyebox from large lateral displacements, forexample, from near the frame of augmented reality glasses, with improvedillumination uniformity of the eyebox. In some examples, a highrefractive index optical element may include gallium phosphide (GaP),though other materials may be used (e.g., other phosphides, arsenides,nitrides, oxides, and the like). In some applications, the light sourcesmay be part of augmented or virtual reality headware, such as LEDs orlasers embedded in the lenses or frames of augmented reality glasses. Insome examples, the optical configurations may help prevent totalinternal reflection (TIR) within optical system components, which cancreate unwanted stray glare. In some examples, the angular distributionof directed light may have a sharp cut-off before TIR effects occur.

The following will provide, with reference to FIGS. 1-27B, detaileddescriptions of example devices, methods, and the like. FIG. 1 is aschematic of a device including a light source and an optical element,and FIGS. 2A-2F illustrate optical elements with various exit surfaceconfigurations. FIGS. 3A-3B illustrate illumination uniformity of atarget. FIGS. 4A-4G illustrate fabrication of a light source integratedwith an optical element. FIG. 5 shows an arrangement of light sourcesand associated optical elements on a semiconductor wafer, and FIG. 6illustrates the fabrication of light sources and optical elements usingseparate semiconductor wafers. FIGS. 7A-13C illustrate example devicesincluding a light source, and an optical element, and illumination of atarget using such as device. FIGS. 14-21 illustrate approaches to beamshaping (e.g., of a laser light source) using an optical element thatincludes a metamaterial layer. FIG. 22 shows an example method offabricating a device. FIG. 23 shows an example control system that maybe used in exemplary devices according to some embodiments. FIGS. 24 and25 illustrate exemplary augmented-reality glasses and virtual-realityheadsets that may be used in connection with embodiments of thisdisclosure. FIGS. 26 and 27A-27B illustrate an exemplary device thatincludes eye-tracking.

Features from any of the embodiments described herein may be used incombination with one another in accordance with the general principlesdescribed herein. These and other embodiments, features, and advantageswill be more fully understood upon reading the following detaileddescription.

In some examples, a device may include one or more light sources, suchas a light-emitting diode (LED) or laser, and may include one or morequantum wells, quantum dots, 2D materials, or any other materialproviding an optical transition. Example light sources may emit lighthaving a wavelength within the wavelength range of 400 nm-1600 nm. Anexample light source may also emit light within an emission cone of lessthan 140 degrees.

In some examples, light is emitted through an aperture that is locatedon one of the surfaces of the light source. A light source may have oneor more apertures.

In some examples, a light source may be fabricated using one or moresemiconductor processes, and may be fabricated on a wafer. A wafersupporting one or more light sources may be termed an emitter wafer. Anexample light source may be fabricated on the emitter wafer using one ormore of the following processes: doping, epitaxial growth, oxidation,etching, lithography, exfoliation, and/or any other semiconductorprocess.

Light emitted by the light source may propagate through an opticalelement. The optical element may be located on, adjacent, substantiallyadjacent, or proximate of the light source. For example, the opticalelement may have a surface that is less than 250 microns away from asurface of the light source, such as the emission surface. In someexamples, the optical element may be located directly in contact with alight source surface.

In some examples, an optical element may include a material (e.g., ahigh-index material), such as a semiconductor or a dielectric material.In some examples, the optical element may include a material that has arefractive index (e.g., at an emission wavelength of the light source)that is at least approximately 2, and in some examples the refractiveindex may be at least approximately 3. An example material may have anenergy bandgap that is larger than the photon energies of light emittedby the light source. Example materials include arsenide semiconductors(e.g., GaAs, AlAs, Al_(x)Ga_(1-x)As), phosphide semiconductors (e.g.,GaP, In_(x)Ga_(1-x)P), nitride semiconductors (e.g., GaN, InN, AIN),oxides (e.g., a titanium oxide such as TiO₂), other III-Vsemiconductors, or other II-VI materials.

In some examples, the optical element may have a multi-faceted3-dimensional structure. The size (exterior dimensions) of the opticalelement may be less than 1 mm×1 mm×1 mm, such as less than 300×300×300microns, and in some examples may be less than 250×250×250 microns.

In some examples, light propagates through a minimum of two facets ofthe optical element. A facet may also be referred to as a surface. Lightmay be received by the optical element through a light entry surface,which may also be referred to as the entry surface. One of the facets ofthe optical element, such as the entry surface, may be generally flatand parallel to the emissive surface of the light source, for example,parallel to the plane of the aperture through which light is emitted bythe light source. The light may exit the optical element through a lightexit surface, which may also be referred to as an exit surface. One ormore of the facets of the optical element, such as an exit surface, mayhave a surface profile that may include spherical, aspherical, freeform,anamorphic, generally convex, or generally concave surfaces, or somecombination thereof.

In some examples, the refractive index of the optical element might varyas a function of position within the lens. For example, the opticalelement may include a gradient index (GRIN) portion. In some examples,one or more of the facets of the optical element have a surfacestructure that can be smooth. In some examples, one or more of thefacets of the optical element have a surface structure that can berough. For example, a surface may act as a diffuser. In some examples,the scale of the surface roughness may be less than the wavelength oflight, for example, one or more (e.g., several) orders of magnitudesmaller than the wavelength of light. In some examples, one or more ofthe facets of the optical element have a surface structure that hascontrolled amounts of periodic or aperiodic perturbations, for example,whose periodicity is of the scale of the wavelength of light or smaller.An optical element may have a surface structure that providesdiffractive optics (e.g., a grating structure), or may includemeta-structures, holographic optical elements, or polarization volumegratings or holograms.

In some examples, one or more of the surfaces (that may also be referredto as facets) of the optical element may have a surface structure, andthe surface structure may include predetermined amounts of periodic oraperiodic perturbations. In some examples, a surface structure mayinclude perturbations having a periodicity larger than the scale of thewavelength of light, and may include a surface structure such as amicro-lens array. In some examples, one or more of the surfaces of theoptical element may support a dielectric or metallic coating, forexample, a coating configured to reflect light towards another surface,such as an exit surface through which the light leaves the opticalelement. In some examples, one or more surfaces of the optical elementmay have a surface structure with periodic or aperiodic perturbations toreduce visible glints. A surface structure may be created either duringfabrication, for example, as a result of patterned etching, or in apost-fabrication etching or deposition process.

In some examples, a surface (e.g., one or more surfaces) of the opticalelement may have an anti-reflective coating, for example, to reducereflection at a particular facet. An example antireflective coating mayhave low reflectivity for the range of the source wavelengths, or forvisible light, or for both.

In some examples, an example coating may also include scatteringelements (e.g., microparticles, nanoparticle, or other particles). Insome examples, one or more of the facets of the optical element mayreflect light due to, for example, total internal reflection based onthe angle of incidence of the beam or due to a reflective coating suchas a metal film. In some examples, a surface may have a coatingincluding one or more emissive components, such as one or more ofquantum dots, phosphors, fluorophores, non-linear optical materials,lasing materials, or other photoluminescent materials. In some examples,a coating may change the color of the light, for example, by absorbinglight at one wavelength and emitting light at a second wavelength, or bymodifying the wavelength of a light beam using a nonlinear opticaleffect.

In some examples, a light source may be fabricated on an emitter wafer.The emitter wafer may include the substrate layer on which the lightsource is fabricated, and may include a semiconductor such as galliumnitride (GaN), gallium arsenide (GaAs), aluminum gallium arsenide(AlGaAs), other semiconductor, or other dielectric material (e.g.,sapphire, or other oxide), or other suitable material. The term emitterwafer may, in some examples, refer to the light sources while still on awafer, after fabrication. An emitter wafer may also include one or moreof the following: passivation layers or other features (e.g., SiO₂),metallic bond pads (e.g., Au, Ag, Cu, other metals), quantum wells,distributed Bragg gratings, dielectric coatings, and/or a backplane suchas glass, silicon, or metal.

In some examples, the optical element may be fabricated directly on theemitter wafer, for example, using one or more semiconductor processes,such as chemical vapor deposition (CVD), physical vapor deposition(PVD), lithography, or etching (e.g., dry or wet etching).

In some examples, the optical element may be fabricated on a differentsubstrate (e.g., a semiconductor or glass carrier wafer) from theemitter wafer. The optical element may be fabricated using one or moreprocess such as spatially modulated UV, optical, or e-beam lithographicexposure, with masks, using direct laser writing, etching (e.g., dry orwet etching), or another lithography process, or with a direct machineprocess such as diamond machining, focused ion beam milling, or laserablation. In some examples, the size of a wafer may be less than 1 inchin diameter.

An optical element, substrate (including, e.g., a wafer), and/or a lightsource may include a semiconductor material. The semiconductor material(e.g., used for the optical element) may be an arsenide semiconductor(e.g., GaAs, AlGaAs, etc.), a phosphide semiconductor (e.g., GaP), orother III-V semiconductor, or a II-VI semiconductor (e.g., a selenide,sulfide, or other chalcogenide material).

Example optical elements fabricated on a semiconductor wafer may bediced using a laser dicer, dicing saw, or similar process, intoindividual units. The individual units can be deposited and positionedon top of the surface of an individual light source using a pick andplace process. The individual units can be bonded to the light sourcesurface using an organic adhesive, such as epoxy or UV curable resin. Insome examples, the individual units can be bonded to the light sourcesurface without adhesives, using an approach such as direct waferbonding, surface activated bonding, or plasma activated bonding.

In some examples, the optical elements may be patterned on an opticalelement wafer with the same spacing and periodicity as the light sourceson the emitter wafer. The optical element wafer may be picked and placedand positioned to some tolerance based on design on top of the emitterwafer, for example, through the use of fiducials. The optical elementwafer may then be bonded to the emitter wafer, for example, usingorganic adhesives such as an epoxy or a UV curable resin. In someexamples, the optical element wafer may be bonded to the emitter waferwithout adhesives, for example, using an approach such as direct waferbonding, surface activated bonding, or plasma activated bonding. Afterbonding the wafers together, the individual light source/optical elementcombination units may be diced, for example, using a laser dicer ordicing saw. In some examples, a sacrificial layer may be deposited ontop of the emitter wafer, and may be planarized, for example, with aprocess such as chemical-mechanical polishing.

In some examples, the optical element may include a semiconductormaterial, such as a semiconductor layer or other semiconductor element,grown directly on the top surface of the emitter wafer. A semiconductormaterial may be deposited by any appropriate process, for example, byCVD, PVD, or another deposition technique.

In some examples, an optical element may be fabricated from asemiconductor layer using one or more semiconductor fabricationprocesses, such as lithography or etching (e.g., dry or wet etching).Similar approaches may be used for fabricating metamaterial layers, forexample, as part of an optical element.

Examples include devices, systems, and processes related to opticalelements. In some examples, a device includes a light source, such asLED or laser. The light source may have a cross-section that is smallerthan 300×300×300 microns in size. Additional examples include a lightsource and an additional optical element, such as a beam-shaping opticalelement.

In some examples, an optical element is used to modify light emissionfrom a light source, such as an LED or a laser. An optical element mayinclude a structured or unstructured material that is used to interactwith light. An optical element may include, but is not limited to,refractive optics, reflective optics, dispersive optics, polarizationoptics, diffractive optics, and gradient index materials.

FIG. 1 shows an example device generally at 100, including a lightsource 110, configured to emit light from an emissive surface at 115that is directed into an optical element 120 (e.g., a beam-shapingoptic). The optical element 120 may be surrounded by air, or, in someexamples, may be encapsulated in an optical medium, such as a glass,plastic, or other surrounding medium (not shown). The optical element120 may have a freeform surface 140 configured to redirect (deflect) andshape the internal light beam 130 within the optical element to form thelight beam 150. The light beam 150 may be used to illuminate a target(not shown), such as an eye.

FIGS. 2A-2F show example optical elements that may be used forbeam-shaping and/or redirection of a light beam. The lines extendingfrom light sources and entering respective optical elements representlight rays. Light rays within an optical element are shown as slightlythinner lines.

FIG. 2A shows a device 200 including a light source 202 and an opticalelement 204. The optical element 204 may have an planar entry surface208, through which light enters the optical element, and an a tilted (oroblique, or “prismatic”) exit surface 206, through which the light beam210 exits the optical element. In this example, the optical element maybe termed a prismatic optical element, or a refractive prism.

FIG. 2B shows an example device 220 including a light source 222 and anoptical element 224. The optical element may have a planar entry surfacethrough which light from the light source enters the optical element,similar to that shown in FIG. 2A. The optical element may have afreeform exit surface 226 through which the light beam (labeled “Light”)leaves the optical element. The optical element may be referred to as afreeform optical element, or a freeform lens.

FIG. 2C shows an example device 230 including a light source 232 and anoptical element 234. The optical element may include a microlens arraypair-based Kohler diffuser. The optical element may include microlenselements, such as microlens element 236 within the entry surface, andthe microlens element 238 on the exit surface. The microlens elementsmay be formed on opposite sides of a generally transparent sheet. Lightexiting the optical element is shown incident on illuminated surface240, but targets in other locations may be illuminated.

FIG. 2D shows an example device 260 including a light source 262 and anoptical element 264. Light enters the optical element, is internallyreflected from surface 266, and leaves the optical element through exitsurface 270, forming beam 268. The optical element allows illuminationof a target that is laterally displaced from the light source. However,internal reflection from exit surface 270 may lead to stray light rays.

FIG. 2E shows an example device 280 including a light source 282 and anoptical element 284. In this example, the optical element 284 includes aturning film, having a plurality of prism elements 286 located on aplanar substrate 288. The planar substrate 288 provides a planar entrysurface for light to enter the optical element, and the light may thenbe redirected by oblique surfaces of the prism elements 286. Thisconfiguration allows illumination of a laterally displaced target (notshown). However, stray light may illuminate regions outside of thedesired target area, for example, due to multiple reflections of lightrays (shown as solid lines) from interior surfaces of the prism elements286.

FIG. 2F shows an example device 290 including a light source 292 and anoptical element 294. In this example, the optical element may include adecentered plano-concave lens. The generally concave surface 296 may bea generally spheric surface, or an aspheric surface (such as a freeformsurface).

In some examples, an encapsulant layer (discussed further below, inwhich the optical element may be, at least in part, embedded) mayinclude a decentered generally concave surface, such as that shown at296. A decentered concave surface may have an optical center (or opticalaxis) laterally displaced from the light source.

In some examples, an optical element may be embedded in an encapsulantlayer having a decentered concave surface, for example, similar to thatshown in FIG. 2F. In this context, the term decentered may refer to alight source and/or optical element not located on the optic axis of theconcave surface.

FIGS. 3A and 3B show example qualitative light distributions created inthe far field by different types of beam-shaping optical elements. FIG.3A may represent illumination intensity for a freeform surfaceconfigured to illuminate the eye from a lateral offset of 18 mm. FIG. 3Bmay represent illumination intensity for a freeform surface configuredto illuminate the eye from a lateral offset of 18 mm. Freeform opticalelement configurations are discussed further below.

FIGS. 4A-4G illustrate example methods of fabricating an opticalelement, such as a prism structure, on top of light source. FIGS. 4A-4Eillustrate fabrication of a prismatic optical element on top of a lightsource. In this example, the light source may be a vertical-cavitysurface-emitting laser (VCSEL). The optical element may include asemiconductor, such as an arsenide semiconductor, such as aluminumgallium arsenide (AlGaAs). FIGS. 4F-4G illustrate fabrication of anotherexample optical element.

FIG. 4A shows a light source at 400, including substrate 410, n-dopeddistributed Bragg reflector (n-DBR) 412, optional confinement layer 414,oxide layer 416, quantum well structure 402, p-doped distributed Braggreflector (p-DBR) 418, and contact layer 420. A passivation layer 422may be formed on the contact layer. There may optionally be confinementlayers formed on each side of the quantum well structure. The quantumwell structure may include a stack of alternating barrier layer andquantum well structures, and may include GaAs quantum wells and AlGaAsbarrier layers. The oxide layer 416 may help define the lateral extentof the quantum well structure. The emissive surface of the light sourcemay be located within the top surface (as illustrated) of thepassivation layer 422.

After the distributed Bragg reflectors 412 and 418 (or other similargrating structures) are fabricated, and the passivation layer 422 isdeposited, a layer (e.g., a layer including a high-index material suchas GaAs, or AlGasAs) may be deposited on top of the passivation layer,for example, using epitaxy or another method.

FIG. 4B shows the light source 400 (as discussed above in relation toFIG. 4A) having a layer 424 (e.g., a high-index layer) formed on thepassivation layer 422.

Subsequently, a resist layer (e.g., a photoresist layer) may bedeposited on the layer 424, for example, using spin-coating or any othersuitable method. Using a lithographic method, the resist layer may beshaped to a desired 3-dimensional profile, which may be termed the shapeof the resist layer.

FIG. 4C shows a shaped resist layer 426 formed on the layer 424. In thisexample, the resist layer has a generally prismatic shape. However,other shapes may be provided, as desired. For example, an arrangement ofresist droplets may be used to provide microlens elements.

The shape of the resist layer 426 may then be transferred into the layer(e.g., a high-index layer that may include a semiconductor), forexample, by etching. Any appropriate etching method may be used.

FIG. 4D illustrates a reactive ion etching (RIE) process which transfersthe shape of the resist layer (426 in FIG. 4C) into the layer (424 inFIG. 4C) to form an optical element 430, in the form of a shaped layer,associated with the light source 400 (of FIG. 4A). The optical element430 includes an upper prismatic portion, having the shape of the resistlayer before etching, and a planar un-etched portion, which may betermed an optical layer, shown at 428. The latter is optional, and thethickness of the optical element may be any suitable value. In someexamples, the fabrication process may be modified to include ametamaterial layer between the light source and the optical element, orwithin the optical element (e.g., between an optical layer and aprismatic element).

The bond-pad contacts may then be metalized. FIG. 4E shows metal layers432 formed on the contact layer 420. In this example, the opticalelement 430 is integrated with the light source into a monolithic device440, which may be termed a light source module.

The process approach described above in relation to FIGS. 4A-4E may bemodified to form other shapes of optical elements.

FIG. 4F shows an alternative configuration showing formation of adifferently shaped optical element on the surface of a light source 450.Similar to the light source 400 shown in FIG. 4A, the light source 450may be a vertical cavity surface-emissive laser including a quantum wellstructure 452, substrate 460, n-DBR layer 462, oxide layers 464 and 468,optional confinement layer 464, p-DBR layer 470, and passivation layer472. A layer 474 (e.g., a high-index layer, or other lens material) maybe formed on the passivation layer 472. A shaped resist layer 476 maythen be formed on the layer 474.

FIG. 4G shows etching of the device described above, for example, usingreactive ion etching (RIE). The etching transfers the shape of theresist layer 476 into the layer 474, to form an optical element 480. Theoptical element may include material from the layer 474, may have ashaped based on the shape of the resist layer 476, and/or may include ashaped high-index layer. The optical element 480 may be formed directlyon the emissive surface of the light source 450, and has an exit surface482 through which a light beam from the light source may leave theoptical element. The combination of a light source, and an opticalelement formed directly on the light source, may be termed a “lightsource module” or more concisely as a “module”.

In this example, the optical element 480 has an tilted exit surface,that may also be termed an oblique exit surface or a prismatic exitsurface. The optical element may be referred to as a prismatic opticalelement. In some examples, the optical element may have a curved exitsurface, such as an aspheric or freeform surface. Curvature of the exitsurface may be achieved using a variety of suitable resist patterns andetching processes. For example, the resist element may be formed with acurved surface that may then be transferred by an etching process into asurface of an optical element. In some examples, a prismatic exitsurface, configured to provide beam redirections, may be combined with ametamaterial layer configured to provide additional beam shaping.

In some examples, a metamaterial layer may be included within theoptical element 480. In some examples, a metamaterial layer may beformed on the surface of the light source, and the optical element maybe formed on the metamaterial layer. In some examples, an optical layer(such as a high-index layer) may be formed on an emissive surface of thelight source, a metamaterial layer may be formed on the optical layer,and a prismatic element (such as a wedged element, e.g., similar toelement 480) may be formed on the metamaterial layer. Metamateriallayers are discussed in more detail below. In some examples, a structure(such as described below in relation to FIG. 18) may be formed on thelight source.

FIG. 5 shows a schematic representation of an arrangement of lightsource modules 510, with each light source module including an opticalelement formed on a light source (e.g., formed directly onto an emissivesurface of a light source), arranged as an array of light source modules510 on a semiconductor wafer 500. After processing, individual lightsource modules, or arrays of light source modules, can be created, asdesired, by dicing. The individual modules may include an opticalelement located on or proximate the emissive surface of a light source.The dot pattern represents an array of possible light source modulelocations, where the dots fall within the extent of the wafer 500.

FIG. 6 shows another example approach. In this example, light sources620 may be processed on wafer 600, and optical elements 630 may beprocessed on a different (second) wafer 610. Both wafers can be alignedand bonded to each other such that each optical element is positioned atan appropriate location with respect to the emissive surface of arespective light source. For example, an optical element may be locatedso that the optical element receives light through an entry surface froma substantially adjacent light source, and so that light leaves theoptical element through an exit surface. In some examples, an opticalelement may be bonded to a light source (or an associated structure)using an adhesive, such as a polymer or photopolymerizable adhesive, orother adhesive resin that may be cured with UV and/or heat. Alignmentbetween light sources and respective optical elements may be facilitatedusing fiducial marks on one or both wafers. Appropriate lateralpositioning tolerances may be determined by the photomasks used.Positional alignment normal to a wafer surface may be controlled usingsuitable spacers, as needed.

FIG. 7A is a schematic of a device 700 including a light source 710(e.g., a light-emitting diode or a laser) that may be supported on atransparent substrate (not shown). Light from the light source 710enters an optical element 730, which may include a high-index material,that is encapsulated in encapsulant layer 720. The light may passthrough the encapsulant layer 720, forming a distribution of light rays740 that are emitted into the environment outside of the encapsulantlayer. An optional external element, such as prismatic structure 750,may be included to further modify the beam profile, for example, toreduce hot spots. The dashed lines may represent a cone within whichlight rays are emitted by the combination of the light source and theoptical element.

In some examples, an encapsulant layer may include an optical medium inwhich the optical element is embedded. The encapsulant layer may have acurved exit surface, for example, a generally concave exit surface, fromwhich light generated by one or more light sources exits the encapsulantlayer to illuminate a target, such as the eye of a user of a wearabledevice (such as a head-mounted device, e.g., when the user is wearingthe device).

FIG. 7B shows an example beam profile for a light source embedded in anencapsulant layer (e.g., an intermediate refractive index medium), suchas the light source discussed above in relation to FIG. 7A. In someexamples, the light beam may leave the optical element through an exitsurface and into the encapsulant layer. In some examples, the light beammay pass through the exit surface of the optical element, and into air.

FIGS. 8A-8C show the illumination of a target using a light source incombination with an optical element having a planar lower surface and anoblique top surface (e.g., not parallel to the planar lower surface).The exit surface of the optical element may be termed a prismatic exitsurface, and may resemble the optical element discussed above inrelation to FIG. 2A. The lower surface of the optical element may be abeam entry surface through which a beam enters the optical element. Theoblique exit surface may provide beam deviation, in which the directionof the beam may be changed by refraction, for example, at an interfacebetween an optical element material and a relatively low index materialof the encapsulant (or air) . The optical element may have prism-likeproperties.

FIG. 8A shows a device 800 including a light source module 810 (e.g., acombination of a light source and an optical element). The light sourcemay be configured to emit a light beam along the vertical direction(relative to the figure), and the optical element may be configured toredirect the light beam along an oblique direction. The light sourcemodule provides light beam 820 that passes along an oblique directionthrough the encapsulant layer 830. A ray bundle 850, emerging from theencapsulant layer 830, may illuminate a target 860. The ray bundle 850may also be referred to as a light beam illuminating the target. Thetarget may include an eye box of a user. The encapsulant layer may havea generally concave surface 840, and the device may form projected lightrays 870, 880, and 890 within ray bundle 850, for example, to illuminatethe target 860.

In some examples, using an optical element having a prismatic exitsurface, the projected ray density of the three rays 870, 880, and 890on the target 860 may show reduced illumination density with increasingangles. In some examples, the illumination intensity may be improvedusing an optical element having a freeform exit surface, or by modifyingthe exit surface curvature of the encapsulant layer.

FIG. 8B qualitatively illustrates an example illumination uniformity,for example, for light illuminating the target 860 using the devicediscussed above in relation to FIG. 8A. The Y-axis and X-axis of thegraph represent the vertical and horizontal directions, respectively.However, axis labels for this representation, and for other examples,may be arbitrary. Example devices, such as described above in relationto FIG. 8A, may provide reasonably uniform illumination over the targetregion 860. In some examples, uniformity along an orthogonal direction(that may be denoted z) may also be improved.

FIG. 8C further illustrates illumination uniformity, in terms ofirradiance level along a spatial axis. The figure illustrates(qualitatively) the relative illumination intensity along the Y-axis.

FIGS. 9A-9B show the illumination of a target using a light source incombination with an optical element having a planar lower surface and afreeform top surface (e.g., an aspheric surface lacking rotationalsymmetry). The optical element may provide both beam redirection andalso improve the illumination uniformity of a remote object, which maybe referred to as a target. This is illustrated by the relativelyuniform spacing between the beams as they illuminate the target.

FIG. 9A shows a device 900 including a light source module (e.g., acombination of a light source and an optical element) located at 910, atleast partially embedded in encapsulant layer 920, and configured toproduce a ray bundle 950 (or light beam) that illuminates the target960. In this example, the encapsulant layer has a planar exit surface.In some examples, the optical element may have a freeform exit surfacethat improves the illumination uniformity of the target.

FIG. 9B shows a qualitative representation of the illuminationuniformity using a device such as that described above in relation toFIG. 9A.

FIGS. 10A-10D further show the illumination of a target using a deviceincluding a light source and an optical element with a curved exitsurface.

FIG. 10A shows, in a cross-sectional schematic, a device 1000 includinga light source 1002 and an optical element 1006. Light from the lightsource 1002 enters the optical element through entry surface 1004 (here,a planar entry surface), passes through the optical element 1006, andleaves the optical element through the exit surface 1008. In thisexample, the exit surface is a freeform surface. The exit surface 1008curves in the plane of the cross-section, and also includes a portion1010 curving backwards (as illustrated) towards an upper portion 1012. Aray bundle (or light beam) 1014 emerges out of the optical element 1006,through the exit surface 1008, and is directed to illuminate a target(not shown).

FIG. 10B shows a device similar to that discussed above in relation toFIG. 9A, though in this example the encapsulant layer has a generallyconcave exit surface. The example device 1020 includes a light sourcemodule 1022 (including a light source and optical element), and anencapsulant layer 1030 having a generally concave exit surface 1040. Alight beam 1024 passes through the encapsulant layer 1030, and emergesat an oblique angle from the light source module. A ray bundle 1050 (ortarget-illuminating light beam) emerges from the encapsulant layer 1030,including rays such as 1070, 1080, and 1090 that illuminate the target1060.

FIG. 10C qualitatively illustrates an example illumination uniformity,for example, for light illuminating the target 1060 in FIG. 10B. Axislabels for this illustration, and for other examples, may be arbitrary.An example device, such as described above in relation to FIGS. 10A-10B, may provide reasonably uniform illumination over a target.

FIG. 10D further illustrates illumination uniformity in terms ofirradiance level along a spatial axis. The figure illustrates(qualitatively) the relative illumination intensity along a particulardirection, labeled as the Y-axis.

FIG. 11 shows an example device 1100 having a substrate 1110 (which mayhave the shape and dimensions of an eyeglass lens, and may include atransparent substrate) having an arrangement of light source modulessuch as 1120, 1130, and 1140. A light source module may include a lightsource combined with an associated optical element (e.g., a highrefractive index microscale optical element). The light source modulelocations may be distributed over the substrate 1110 in a pre-determinedarrangement, relative to the shape of the transparent substrate. Theconcentric circles illustrate radial distances of 18 mm, 36 mm, and 50mm, that may be, for example, approximate radial distances from theoptical center of a lens, and/or from the optical center of the eye of auser. The light source modules 1120, 1130, and 1140 are shown at examplelocations, and other locations may be used, for example, arranged aroundone or more predetermined radial distances. A frame, such as a portionof an eyeglass frame, may extend around the substrate, and may beconfigured to support the device on the head of a user.

In some examples, a device may include a frame, for example, the frameof augmented reality glasses. The frame may include one or more lenses.A lens may include a prescription lens or a plane window. Light sourcesmay be distributed around the lens, for example, at various radii fromthe optical center. Light sources may have a cross-sectional area lessthan 300×300 microns, and may not be easily perceptible within a user'sfield of view. The optical elements may be arranged to direct lightbeams from the light sources towards the eyebox; i.e., a region aroundthe center of the eye that may include the pupil. Example opticalelements may improve the illumination of the eyebox, for example, toprovide more uniform illumination. Light may be reflected from the eye,detected using an arrangement of optical sensors, and used for eyetracking. Example devices and systems may allow determination of thepupil periphery, gaze direction, and the like.

FIG. 12 shows a schematic of a cross-section of an example deviceshowing the illumination from an eye-tracking device 1200 on a target1240 that may represent a user's eye. The eye-tracking device may be,for example, similar to the device discussed above in relation to FIG.11. The figure shows light source modules, for example, at 1210. A lightsource module may include a combination of a light source and an opticalelements, which may be at least in part embedded within encapsulantlayer 1220. In this example, the exit surface 1250 of the encapsulantlayer, facing the eye, has a generally concave shape. The light sourcemodules may provide light beams such as 1230 and 1235. Differentpatterned lines are used to show illumination patterns of differentlight source modules. The encapsulant layer, and the light sourcemodules, are supported on a substrate 1260. In some examples, thesubstrate may be a transparent substrate, and may provide a lens orwindow of a device, such as a device also including a near-eye display,and may have curved and/or planar surfaces. The substrate, encapsulantlayer, and other components, such as those described above, may besupported in a frame 1270. In some examples, light sources and/or anencapsulant layer may be supported by the frame, and the substrate maybe omitted. The substrate may be transparent for augmented realityapplications, and may be provided by a window or a lens supported by aframe in an eyeglass-based device. In some examples, a substrate may notbe transparent, for example, as part of a virtual reality device. Insome examples, the frame 1270 may extend around the periphery of thelens, and may be part of an eyeglass shape. The shape of the frame maybe similar to that of the periphery of the shape shown in FIG. 11. Insome examples, may have two planar surfaces, which may be generallyparallel as shown in the figure, but in some examples at least onesurface of the substrate may be curved. In some examples, the substratemay be a transparent substrate. The substrate may be configured to allowone or more of the following to pass through the device and reach theeye of a user: light from the ambient environment (the “real world”),augmented reality image light, and/or virtual reality image light.Example optical elements may be configured to provide differentdeviation angles based on the locations of the optical element andassociated light source. For example, combinations of light source andoptical elements may be configured so that the optical element providesa larger deviation angle for larger lateral offsets from the eyebox. Insome examples, a light source may be configured to produce a beam atleast partially directed towards the eyebox.

A light beam generated by a light source may have an initial direction,that may, for example, be generally normal to a proximate substratesurface, and/or normal to the entrance surface of the optical element.The beam direction may be considered as the mean or average beamdirection, though an example light source may provide a light beamwithin an emission cone. In some examples, light sources and associatedoptical elements may be distributed over a device, such as wearableaugmented reality device or a virtual reality device.

FIGS. 13A-13C show example devices including a combination of a lightsource and an associated optical element. The optical element mayinclude a high-index material, for example, a material having arefractive index greater than approximately 2, such as a material havinga refractive index of at least approximately 3. The optical element mayinclude a semiconductor, such as gallium arsenide (GaAs, refractiveindex, n=3.5), aluminum gallium arsenide, other arsenide semiconductor,other semiconductor material, or other material such as a high-indexmaterial.

FIG. 13A shows a portion of a device 1300, including light source 1310,optical element 1320, having exit surface 1322, and encapsulant layer1330. The combination of light source 1310 and optical element 1320produce light ray bundle 1340, which is refracted at the exit surface1344 of the encapsulant layer, to provide target-illuminating ray bundle1342. In some examples, the exit surface 1344 of the encapsulant layermay have a generally concave profile. The figure also shows atransparent substrate 1346 that may support the light source and may beadjacent the encapsulant layer. A frame (not shown) may be used tosupport the device, for example, on the head of a user, the target mayinclude an eye of the user, and the device may be an eye-tracking deviceor a device having an eye-tracking function. In some examples, thethickness of the encapsulant layer may be between approximately 0.5 mmand approximately 5 mm.

FIG. 13B shows an example device 1350. The device may include a lightsource 1352 providing a light beam 1354 that enters the optical element1360 through entry surface 1356. The light beam 1364 propagates throughthe optical element 1360, which may include a high-index material (thatmay be a generally transparent material) 1358, and is refracted at theexit surface 1362 of the optical element 1360 into the encapsulant layer1370 as light beam 1366. The exit surface of the encapsulant layer isnot shown in this figure, but the light beam 1366 may exit theencapsulant layer 1370 and may illuminate a target such as an eye (notshown in this figure). In this example, the optical element 1360 has anentry surface 1356 that may be a planar surface and an exit surface 1362that may be a freeform surface.

FIG. 13C shows a device 1380 including a light source 1382 and anoptical element 1384, both of which may be (at least in part)encapsulated in an encapsulant layer (not shown). The optical element1384 may have an aspheric exit surface, such as a freeform surface 1386,through which a light beam may leave the optical element that bothchanges the chief ray angle for light emitted by light source 1382 andmodifies the relative ray angles within the ray bundle 1388, forexample, for light rays 1390, 1392, and 1394. This curved exit surfaceconfiguration may provide improved uniformity of illumination of atarget, particularly when the target is laterally offset from the lightsource and the illumination is from oblique angles.

For example, a light source may be offset laterally relative to thecenter of the illumination target region (e.g., the light source mayhave a radial offset from the center of the eye, for example, asdiscussed in relation to FIG. 11). The curved output surface of theoptical element may be a freeform surface and may lack rotationalsymmetry (e.g., around the optic axis and/or chief ray of input oroutput light beams). In some examples, the exit surface may be ananamorphic aspheric surface. In some examples, the exit surface mayinclude a curved interface between the optical element and asubstantially adjacent encapsulant layer.

However, in some examples, similar properties and advantages as thoseprovided by a freeform optical surface may be obtained using acombination of an oblique exit surface (such as that obtained using awedge element) and a metamaterial layer. An oblique exit surface maymodify the chief ray angle, for example, imparting a deviation ofbetween 10 degrees and 80 degrees, such as between 20 degrees and 60degrees. A metamaterial layer may modify the relative ray angles withinthe ray bundle to improve illumination uniformity of a target (such asan eye). Optical elements including a metamaterial layer are discussedfurther below.

In some examples, a device may include a light source (e.g., supportedon augmented reality and/or virtual reality headwear, such as a headset,glasses, or the like) providing a light beam to an optical element. Insome examples, the beam may be redirected towards the eyebox by theoptical element. The optical element may be embedded in a medium, suchas an optical polymer, having an intermediate refractive index. Theoptical element may have a planar surface through which the beam entersthe optical element, and an exit surface (such as an oblique planarsurface, or a freeform curved exit surface) through which the beamleaves the optical element. Refraction at the interface between theoptical element and the surrounding medium (e.g., air, polymer or othermedium) may deviate the path of the beam towards a laterally offsettarget. The high-index material may include a semiconductor, such asGaAs (refractive index, n=3.5), AlGaAs, or one or more other arsenidesemiconductors.

In some examples, the optical element may include a semiconductor suchas a phosphide semiconductor, for example, gallium phosphide (GaP), thatmay have a refractive index of approximately 3.1. An example opticalelement may include one or more semiconductors, such as one or more ofthe following semiconductors: arsenides, phosphides, nitrides,antimonides, selenides, sulfides, or other semiconductors.

In some examples, metamaterial layers (which may, in some examples, alsobe termed metalayers or metasurfaces) may be used for beam shaping, forexample, in eye-tracking beam shaping applications.

Example eye-tracking devices may include a VCSEL (vertical-cavitysurface-emissive laser). A beam-shaping element may be used to enableuniform and distributed illumination to eyeboxes. In some examples, beamshaping may be achieved through wavefront manipulation using ametamaterial layer. In some examples, an eye-tracker may include one ormore optical detectors, such as a photodetector or an imaging sensor,and a control module configured to determine an orientation of the eyefrom detected radiation returned from the eye.

An example device may include one or more light sources, with each lightsource used in combination with an optical element. Example lightsources, such as an LED or laser, may have a light source emitting areahaving a size smaller than 1 mm×1 mm, such as less than 300×300 microns.Control of the emitting area may be achieved using one or more ofetching, electrical confinement, or optical confinement. In someexamples, a light source package size may be smaller than 1 mm×1 mm×1mm, such as smaller than 300 microns×300 microns×300 microns indimension.

In some examples, an optical element may include a metamaterial layer.Unlike a freeform refractive element, a metamaterial layer may be flat,and generally uniform in thickness, that may allow for fabrication usingconventional semiconductor processing. An example metamaterial layer isconsidered, which includes a distribution of nanopillars (having eithera cylinder, square, or other cross-sectional shape) with a pillarspacing less than the operating wavelength of the light source. The size(such as the diameter) of the nanopillars may be adjusted to accommodatethe phase variation required for a desired wave-front manipulation. Thephase retardation for nanopillars can be calculated as a function ofnanopillar diameter using simulation tools such as finite-differenttime-domain (FDTD) methods, rigorous coupled-wave analysis (RCWA), andthe like. The metamaterial layer may thus direct and/or diverge the beamas appropriate for the device application, such as an eye-trackingapplication.

In some examples, a device includes a laser, such as a VCSEL. In someexamples, a laser may operate in the near-IR. In some examples, thelight source may include a GaAs VCSEL, though this and other examplesare non-limiting. In some examples, the metamaterial layer may belocated within the substrate material of the laser, such as a VCSEL,that may be based on GaAs. In some examples, a metamaterial layer may belocated on (or otherwise supported by) a surface of the substrate.

FIG. 14 shows beam shaping of an example light source (e.g., a VCSEL)using a device including an optical element, where the optical elementincludes a metamaterial layer. FIG. 14 shows a device (or a portion of adevice) 1400, including a light source (or light-emitting element) 1420,such as a VCSEL, having a light-emitting surface 1425, located within asubstrate 1410. The device includes a metamaterial layer 1430, which maybe an external layer on top of the substrate, or a component of thesubstrate. In some examples, the metamaterial layer 1430 may besurrounded by a generally uniform layer 1440. The metamaterial layer mayextend over the light emitting surface 1425, so that most orsubstantially all light from the light source passes through themetamaterial layer. The metamaterial layer may be formed in situ, or ametamaterial layer may be formed elsewhere by any process and thenpositioned on or within the substrate. The metamaterial layer 1430 andthe light-emitting surface 1425 may be separated by a separationdistance, labeled “d” in the figure. The separation distance may be inthe range 0-1 mm, such as 10 nm-500 microns, such as 10 nm-10 microns.These ranges, and others, are exemplary and not limiting, may beapproximate ranges, and/or may be inclusive ranges. In some examples,the substrate itself may be the light-emitting element.

In FIG. 14, example light rays are shown as solid lines emerging fromthe light source 1420, and passing through the metamaterial layer 1430.In this example, the optical element includes a metamaterial layerconfigured to obtain a desired beam profile, such as a beam profile thatprovides improved illumination uniformity. The light source 1420provides a light beam that may illuminate an optical element includingthe metamaterial layer 1430. The metamaterial layer 1430 may include anarrangement of microstructures or nanostructures, such as an arrangementof pillars or other structures.

In some examples, the metamaterial layer may be located within thesubstrate. In some examples, the metamaterial and the light source maybe adjacent or substantially adjacent. An example metamaterial layer maybe generally planar, and the exit surface of the metamaterial layer,through which light exits after passing through the metamaterial layer,may be generally planar. In some examples, an optical element mayinclude one or more metamaterial layers, and optionally one or moreadditional optical layers and/or additional optical components (such asa wedge element, grating, filter, aperture, lens, or other opticalcomponent). In some examples, an optical element may include ametamaterial layer combined with a wedge element. For example, a wedgeelement may be located on a metamaterial layer, or a metamaterial layerformed on a wedge element.

In some examples, a light source may provide a light beam thatilluminates an optical element, such as an optical element including oneor more metamaterial layers. Example metamaterial layers may include anarrangement of microstructures or nanostructures, such as an arrangementof pillars or other structures. The microstructures or nanostructuresmay include one or more of many possible structure geometries or shapes.A metamaterial layer may have one or more function, such as beamredirection, beam shaping, phase modification, and/or may havepolarization dependent properties. Example metamaterial layers mayinclude polarization-sensitive structures (such aspolarization-sensitive nanostructures) which may include rectangularstructures, oval cross-section structures, coupled structures, or otheranisotropic structures (e.g., nanopillars with an anisotropiccross-section), and/or may include polarization-insensitive structures,such as nanoposts (e.g., nanopillars), square cross section posts, andother structures that possess lateral (x-y) symmetry. The diameter (orequivalent cross-sectional dimension), spacing, and/or length of thestructures (e.g., pillars or other structures) may have a spatialvariation configured to impart a desired beam modification. In someexamples, the exit surface of a metamaterial layer may have an oblique(tilted) exit surface, for example, arising from a spatial distributionof structure height, such as pillar height. In some examples, themetamaterial layer may have a generally uniform thickness. Refraction oflight at the exit surface, and/or spatial variations in phase propertiesarising from metamaterial property variations, may be used to modify thebeam profile and the beam direction.

FIG. 15 shows a view of an example arrangement 1500 of nanopillars (suchas 1540, and 1550) on the surface 1530 of a substrate 1520. In thisexample, the device includes cylindrical nanopillars having a spatiallyvarying nanopillar diameter. For example, nanopillar 1540 has a largerdiameter than nanopillar 1550. In some examples, the arrangement ofnanopillars may be configured as a metamaterial layer. A metamaterialmay include other microstructures or nanostructures. A nanostructure,such as a nanopillar may have a dimension (such as a diameter or otheranalogous cross-section dimension, or other dimension) of less than 1micron. A microstructure may have one or more dimensions less than 1 mm,and in some examples less than 500 microns.

FIG. 16 shows a top view of an arrangement of nanopillars 1600,including nanopillars such as 1610 and 1620. The nanopillars may beconfigured as a metamaterial layer, and may be configured for use with alight source, such as laser diode, such as a GaAs VCSEL.

In some examples, the nanopillars may be arranged in a generally regulararray, such as illustrated in FIG. 16, and metamaterial properties mayhave a spatial variation arising from a spatial variation in nanopillardiameter (or a variation in some other cross-sectional dimension). Forexample, nanopillar 1610 has a greater cross-sectional diameter thannanopillar 1620.

In some examples, a metamaterial layer may have an arrangement ofnanostructures (such as nanopillars), for example, based on an regulararrangement (which may be termed an array or a lattice) with some degreeof symmetry (such as a square lattice, a face-centered square lattice, ahexagonal lattice, etc.). For a high-index substrate, the metamateriallayer may cause some unwanted diffraction. The diffraction may besuppressed using a metamaterial layer having a randomized distributionof nanopillars. The exact position of each metamaterial unit (e.g., ananostructure) may be randomized while keeping the distance betweenneighboring units larger than a minimum value (which may be asub-wavelength distance). A nanostructure parameter (such as a sizeparameter, e.g., a diameter, of each nanostructure, such as ananopillar) may be determined by the phase retardation desired at thenanostructure location.

In some examples, a metamaterial layer may include a randomizeddistribution of metastructures, such as a randomized arrangement ofnanostructures. A metastructure may include microstructures and/ornanostructures, such as nanopillars, other protrusions, or otherfeatures such as holes.

FIG. 17 shows a randomized arrangement 1700 of nanopillars (such asnanopillars 1710 and 1720, having different diameters) configured as ametamaterial layer. In some examples, the location of a nanostructuremay be offset by a randomly selected distance, for example, along arandomly selected orientation, from the location corresponding to aregular array.

In some examples, a metamaterial layer may be combined with one or moreother optical components, such as a wedge element. In beam-shapingapplications where large angles of beam bending (e.g., large refractionangles or beam redirection angles) are required, a wedge element may beadded, for example, on top of the metamaterial layer. The wedge elementmay function as a refractive element that may redirect the beamaccording to the first order of phase retardation. Any higher orderphase retardation may then be achieved using the metamaterial layer.Example configurations may allow the spatial variation in phaseretardation to be lower for the metamaterial layer, potentially enablingmore precise wavefront manipulation.

In some examples, the metamaterial layer may be formed on an obliqueupper surface of the wedge element, or other location, such as on anemissive surface of a light source, or on an exit surface of anencapsulant layer. In some examples, the wedge element may be omittedand beam shaping achieved using a metamaterial layer.

FIG. 18 shows an example device 1800, such as an optical element,including a metamaterial layer 1820, having an arrangement of pillars1822 (such as nanopillars) on a substrate 1830. The device also includesa wedge element 1810. In this example, an optical element may includethe wedge element 1810 (such as a prism or portion thereof), which mayprovide beam redirection. In some examples, the wedge element mayprovide appreciable beam redirection by, for example, redirecting thebeam through an angle between approximately 10 degrees and approximately80 degrees. In some examples, the metamaterial layer 1820 has a spatialvariation in one or more metamaterial parameters (such as pillardiameter and/or pillar spacing), and the spatial variation inmetamaterial layer properties may be used for beam shaping. Beam shapingusing a metamaterial layer may be used, for example, to improveillumination intensity uniformity for a target illuminated by a lightsource located at a laterally offset location, relative to the target.For example, illumination uniformity of an eye using an eye tracker maybe improved using a metamaterial layer in combination with a wedgeelement or other beam redirection element. In this context, a lateraloffset location may be located an appreciable distance from a normal tothe target area, as measured along a direction perpendicular to thesurface normal. Oblique illumination may include illumination using alight beam having an angle between approximately 10 degrees andapproximately 20 degrees to the normal to the target area (e.g., at thecenter of the target area.)

In some examples, the optical element may include the wedge element 1810and the metamaterial layer 1820, and the substrate 1830 may include alight source on which the optical element may be formed. In someexamples, the optical element may include the wedge element 1810, themetamaterial layer 1820, and the substrate 1830. For example, thesubstrate 1830 may include an optical layer, which may include ahigh-index material, or other optical layer, which may be formed on anemissive surface of a light source.

In some examples, a method may include: providing (e.g., fabricating) alight source (such as a laser or a light-emitting diode) having anemissive surface; forming an optical layer (that may include ahigh-index material) on the emissive surface; forming a metamateriallayer on the optical layer; forming a layer on the metamaterial layer;forming a resist layer on the layer, with the resist layer having ashape determined by a spatially non-uniform thickness of the resistlayer; and etching the shape of the resist layer into the layer to forman optical element (which may include material from the layer) having ashaped exit surface. The shaped exit surface may be based on the shapeof the resist layer. The optical element may be supported by theemissive surface of the surface-emissive laser, receive light from thesurface-emissive laser, and may be configured to redirect the light byrefraction through the shaped exit surface to illuminate a remotetarget. In some examples, the optical layer may be omitted. Anadditional example method may include forming a metamaterial layer onthe emissive surface of the light source, forming a layer on themetamaterial layer, formation of a shaped resist layer on the layer, andetching to form an optical element, which may include material from thelayer and may have a shaped exit surface determined by a shape of theshaped resist layer.

In some examples, the metamaterial layer may include an arrangement ofnanopillars having sub-wavelength spacings. The spacings and/ordiameters of the nanopillars may have a spatial variation configured toobtain a desired phase profile. The gaps between pillars may includeair, an inert gas such as nitrogen, or a medium having a significantlydifferent refractive index (e.g., at least 0.5 higher or lower). In someexamples, the metamaterial layer may include elements, such asnanopillars, formed from a material (e.g., a high-index material) suchas a semiconductor. In some examples, gaps between elements may be open(e.g., air filled), or in some examples the gaps may be filled with amaterial, such as an oxide or polymer material.

In some examples, a metamaterial layer may be located on the uppersurface of an optical element, for example, on an exit surface of anoptical element (such as a wedge element).

In some examples, a metamaterial layer may be located on (or near) anexit surface of the light source, or a light source housing, or near theentrance or exit surface of another optical component, such as a wedgeelement. The light source or its housing may have an oblique exitsurface that may help redirect the light beam (e.g., towards the eyeboxin an eye-tracking application). An oblique exit surface may provide asimilar function to a wedge element. In some examples, a wedge elementmay be incorporated into a light source or a light source housing.

In some examples, a reflective surface may be used to direct a lightbeam towards the target, such as the eye, or light box. A metamateriallayer may be located on or near the reflective surface, or locatedelsewhere within the light beam path.

In some examples, a metamaterial layer may be located at any appropriatelocation within the light beam path (e.g., the light beam path from thelight source to the eyebox in an eye-tracking application). Ametamaterial layer may be used in combination with one or more otheroptical components to achieve a desired beam modification of, forexample, one or more of a lens, mirror, phase plate, diffractiongrating, window, optical filter, holographic element, beam shapingoptical element, surrounding medium, or other optical element.

FIG. 19 shows an example phase profile 1900 determined for an examplemetamaterial layer combined with a wedge element, such as the deviceshown in FIG. 18.

FIG. 20A shows a generally periodic arrangement of nanopillars,configured as a metamaterial layer providing the phase variation shownin FIG. 19. The metamaterial layer, shown generally at 2000, includesnanopillars such as 2010 and 2020. In some examples, the nanopillars maybe arranged in a generally regular array.

FIG. 20B shows an example of a randomized distribution of nanostructureswithin a metamaterial layer, also configured to obtain the phasevariation shown in FIG. 18. The arrangement of nanopillars 2050 includesnanopillars such as 2060 and 2070, that are not positionally arranged ona regular array. A metamaterial layer may include a randomizeddistribution of microstructures and/or nanostructures, such as arandomized distribution of nanopillars.

FIG. 21A shows the illumination at far-field using a light source and anoptical element that includes only a wedge element. In this example, theoptical element bends the light beam from the light source to an angleof approximately 40 degrees. FIG. 21B illustrates far-field illuminationusing an optical element that includes a wedge element located on top ofa metamaterial layer. This configuration provides reasonably uniformillumination with a desired wide angular range, in this example overapproximately 0-60 degrees in one direction, and over 100 degrees inanother (orthogonal direction). Hence the use of a metamaterial layer,such as a combination of a metamaterial layer and another opticalcomponent such as a wedge element, may be used to obtain improvedillumination uniformity.

In some examples, a metamaterial layer according to the principlesdescribed herein may include an arrangement of nanostructures, such asnanopillars. The nanostructures may be arranged in a square array orother arrangement. The nanostructure spacing (e.g., the center-to-centerspacing of adjacent nanopillars, that may also be termed a latticeconstant) may be a sub-wavelength distance, for example, in the range0.1 λ to 0.9 λ (where λ is the center emission wavelength of the lightsource), and in some examples may be in the range 0.1 λ to 0.8 λ, andmay be approximately half the emission wavelength. The emissionwavelength may be a near-IR wavelength (e.g., in the range 750 nm-2500nm, such as 750 nm-1000 nm), or a visible light wavelength (e.g., in therange 400 nm-750 nm), for example, a red-orange wavelength (e.g., in therange 590 nm-750 nm). In some examples, a nanostructure dimension (suchas thickness, diameter, or other lateral dimension) may be in the range200 nm-1000 nm, such as between 300 nm and 800 nm, subject to themaximum practical dimension(s) imposed by the choice of latticeconstant. In this context, a lateral dimension may be a dimensionmeasured in a direction orthogonal to a direction of elongation (e.g.,for a nanopillar), and/or measured parallel to a substrate supportingthe nanostructure.

In some examples, a device includes an optical element (e.g., includinga lens or prism and/or a metamaterial layer, that may include ahigh-index material) with a light source (such as a semiconductor lightsource, such as a light-emitting diode, or a laser diode such as aVCSEL). A device may be configured for near-eye operation, for example,as an eye-tracker having a light source located proximate an eye of auser. The emission wavelength of the light source may be a near-IRemission wavelength. In some examples, a device may be configured sothat, when worn by a user (e.g., in a manner suggested by the productlabeling or by convention) the light source is located at a near-eyelocation. The light source may be configured to be located at a distancebetween 5 mm and 50 mm from the eye, for example, at a distance between10 mm and 40 mm from the eye, such as between 15 and 30 mm from the eye,when the device is worn. In some examples, the device may be configuredso that the light source is located less than approximately 25 mm fromthe eye when the device is worn. In this context, a device may be worn,for example, as a self-supporting item (such as glasses, goggles, aheadset, hat, or other item) or as an accessory or a component of suchan item. In some examples, a lens used as (or part of) an opticalelement may have a focal length of between 5 mm and 50 mm, for example,between 10 mm and 40 mm, such as between 15 and 30 mm, and in someexamples the focal length may be less than approximately 25 mm. In someexamples, the device may be configured to be inconspicuous to a user. Insome examples, the light source may have external dimensions less than 2mm×2 mm×2 mm, such as less than 1 mm×1 mm×1 mm, such as less than500×500×500 microns, such as less than 300×300×300 microns. Whencombined with the near-eye proximity, such dimensions may make the lightsources (and, e.g., any associated optical device components)inconspicuous.

In some examples, nanostructures may include one or more materials(e.g., one or more high-index materials), such as one or moresemiconductors. In some examples, nanostructures may include ahigh-index material, such as a semiconductor or a dielectric material.In some examples, the high-index material has a refractive index (at theemission wavelength of the light source) that is greater than 2, and insome examples the refractive index may be approximately 3 or greater. Insome examples, a nanostructure or other metamaterial component mayinclude a material may having an energy bandgap that is larger than thelight source emission photon energy. In some examples, a nanostructureor other metamaterial component may include one or more materials, suchas arsenide semiconductors (e.g., GaAs, AlAs, Al_(x)Ga_(1-x)As),phosphide semiconductors (e.g., GaP, In_(x)Ga_(1-x)P), nitridesemiconductors (e.g., GaN, InN, AIN), oxides (e.g., a titanium oxidesuch as TiO₂, alumina (sapphire), and the like), other III-Vsemiconductors, or other II-VI materials.

In some examples, a device component (such as a nanostructure or othermetamaterial component (such a matrix material used as a surroundingmedium), a microlens, an optical element, a light source, an opticallayer, a lens, or other device component) may include a semiconductor(such as an arsenide, phosphide, or nitride semiconductor), dielectricmaterial (such as an inorganic oxide, nitride, carbide, or the like),ceramic, glass (such as silicate glass or a fluoride glass), semi-metal,or metal. In some examples, a device component (such as a nanostructure,optical element, or other device component) may have a generally uniformcomposition. In some examples, a device may include a gradient-indexcomponent, such as a gradient-index lens.

In some examples, a nanostructure composition may vary within ametamaterial layer. In some examples, a metamaterial or othernanostructure composition may have a non-uniform composition, forexample, including one or more component materials in a layered, ring,hollow, or otherwise non-uniform composition. In some examples,nanostructures may have a composite structure, for example, includingone or more semiconductors and/or one or more metals or othercomponents.

In some examples, nanostructures may be (in whole or in part) embeddedin a matrix material. For example, an arrangement of semiconductornanostructures may be embedded in a matrix layer, such as a layer ofsemiconductor, glass, inorganic material, polymer, or other material.For example, a metamaterial layer may include an arrangement ofnanostructures embedded in layer of matrix material. Nanostructures mayinclude rods (such as nanopillars), particles (such as semiconductorquantum dots, metal nanoparticles, and the like), or othernanostructures. In some examples, a matrix material parameter may varyacross the metamaterial layer. A matrix material parameter may includeone or more parameters such as layer thickness, composition, opticalproperties (such as refractive index, that may be a function ofcomposition), additive fraction, polymerization, molecular conformation(such as isomerism, such as photoisomerism), color, and the like.Nanostructures may be attached (e.g., deposited on) an underlyingsubstrate, or dispersed through the matrix material. The matrix materialmay also be used as a surrounding medium to embed and/or encapsulate thelight source.

In some examples, nanostructures may be formed on a substrate layer orotherwise be located proximate a substrate layer. The substrate layermay have a spatially varying parameter, such as an optical parametersuch as refractive index, thickness (e.g., the example of a wedgeelement), or other variable parameter.

FIG. 22 shows an example method 2200 of fabricating an optical device.The method includes providing a light source (such as a laser orlight-emitting diode) 2210 and forming an optical element on an emissivesurface of the light source (2220), where the optical element issupported by the emissive surface, receives light from thesurface-emissive laser, and is configured to redirect the light toilluminate a remote target. The method may further include illuminatinga target, such as an eye, using a light beam from the light source, withbeam redirection provided by the optical element (2230).

In some examples, a method of illuminating an object, such as an eye,includes providing a light beam by a light source, with the light beamexiting the light source along a first direction, receiving the lightbeam by an optical element, and directing, by the optical element, thelight beam along a second direction towards the object. The seconddirection may be at an appreciable angle to the first direction, forexample, being at a beam redirection angle of between 5 and 70 degrees.The optical element may have an exit surface configured to improve theillumination uniformity of the target.

In some examples, a device may include a light source configured to emita light beam, an optical element configured to receive the light beamalong a first direction and redirect the light beam along a seconddirection, and an encapsulant layer, where the light beam exits theoptical element through an exit surface of the optical element into theencapsulant layer. The optical element may include a high-indexmaterial, and the high-index material may have a refractive index of atleast approximately 1.5 at a wavelength of the light beam, such as arefractive index of at least approximately 2, for example, a refractiveindex of at least approximately 3. The light source may include alight-emitting diode or a laser, such as a surface-emitting laser. Theoptical element may be, at least in part, embedded in the encapsulantlayer. The exit surface of the optical element may have an asphericcurved surface, such as a curved freeform surface having no rotationalsymmetry. The curvature of the exit surface of the optical element maybe configured to reduce an illumination uniformity of a target, forexample, to below 1 standard deviation. An optical element may include amaterial (e.g., a high-index material), such as at least one of asemiconductor or a dielectric material. An example optical element mayinclude at least one of an arsenide semiconductor, a phosphidesemiconductor, or a nitride semiconductor, and/or may include an oxide.An example optical element may include a material that has a refractiveindex of at least approximately 2 at a wavelength of the light beam,and, for example, at a typical device ambient temperature. In someexamples, an encapsulant layer may have an encapsulant refractive indexof between approximately 1.3 and approximately 1.8 at the wavelength ofthe light beam, and may include a polymer, such as an optical polymer.An encapsulant layer may have an approximately concave exit surfacethrough which the light beam leaves the encapsulant layer, for example,to illuminate a target. An example device may be an augmented realitydevice and/or a virtual reality device. An example device may beconfigured so that the light beam is positioned to illuminate an eye ofan intended user of a device. In some examples, an example device mayinclude a plurality of light sources configured to illuminate the eye ofthe intended user, and each light source may have an associated opticalelement. An optical element, and/or a light source, may be at least inpart embedded within an encapsulant layer.

In some examples, a method includes: generating a light beam using alight source; receiving, by an optical element, the light beam;receiving, by an encapsulant layer, the light beam from the opticalelement, with the light beam being refracted by a shaped surface (e.g.,an oblique surface, or an aspheric curved surface such as a freeformsurface) of the optical element; and illuminating a target (such as aneye of a user) using the light beam received from the encapsulant layer.The target may be illuminated by a plurality of light beams, with eachlight beam being generated by a respective light source of a pluralityof light sources. The example method may further include detecting areflected light beam from the target, such as a glint, and may furtherinclude tracking the eye of a user using the detected reflected beam.These example methods may be performed, for example, by an augmentedreality device and/or a virtual reality device.

In some examples, a device includes a light source configured to emit alight beam and an optical element configured to receive the light beamalong a first direction and redirect the light beam along a seconddirection. The optical element may include a high-index material, suchas a semiconductor. The device may be, or include, an eye-trackingdevice. In some examples, the optical element includes a metamateriallayer. The metamaterial layer may include an arrangement ofnanostructures. The nanostructures may have a nanostructure parameter,and the nanostructure parameter may have a spatial variation as afunction of position within the metamaterial layer. This spatialvariation may convey the desired spatial variation in phase retardation,or other optical property. The nanostructure parameter may include oneor more of: a lateral dimension, a cross-sectional area, a lengthdimension, a composition, a nanostructure spacing, a cross-sectionalshape, a cross-sectional shape anisotropy, a cross-sectional uniformity,a taper, a refractive index, a refractive index anisotropy, a coatingthickness, a hollow core thickness, a volume fraction of one or morecomponents, an orientation, or a surrounding medium parameter. In someexamples, the nanostructures may include nanopillars, where thenanopillars have a diameter or other equivalent lateral dimension (suchas an edge length for a polygonal cross-section, such as a square,triangular, pentagonal, or other polygonal cross-section), and thenanostructure parameter may include the nanopillar diameter (or otherequivalent dimension).

Examples include high refractive index, and metamaterial based, opticalelements, for example, including nanostructures, micro-lenses, prisms,and/or diffractive elements. Applications include beam shaping and/orbeam steering of light beams from a light source, for example, ineye-tracking applications. The light source may be a light-emittingdiode or a laser (e.g., a vertical cavity surface-emissive laser orVCSEL). Example high refractive index materials may include one or moreof various semiconductors. Optical elements may be fabricated directlyon the light source, for example, as a metamaterial layer that mayinclude an arrangement of nanostructures having a spatially varyingnanostructure parameter. For example, a metamaterial layer having aspatially varying refractive index may include an arrangement ofnanopillars having a spatially varying cross-sectional diameter. In someapplications, the light sources may be part of augmented or virtualreality headware. For eye-tracking applications, one or more opticalelements may be used to direct a light beam towards the center of theeyebox, for example, with an improved beam shape, improved illuminationproperties such as illumination uniformity, improved glint capture,and/or improved algorithmic pupil edge detection. A device may furtherinclude a wedge optical element to direct the light beam towards theeyebox. In some examples, the optical element may have additionalcomponents, such as an optical coating to modify reflection ordiffraction properties.

In some examples, light sources, such as VCSELs or LEDs, may be locatedat one or more predetermined radii from the center of the eye. In someexamples, light sources may be arranged in one or more rings around thecenter of the eye. Optical elements at each radius (e.g., the lateraldistance between the light source and the eye center) may have adifferent freeform surface design. The freeform exit surfaceconfiguration of an optical element may be modified as a function ofring radius. The optical elements for each light source (e.g., eachVCSEL or LED) on the same ring may be oriented so that the light beam isdirected towards the eyebox.

Examples of the present disclosure include various exemplary highrefractive index optical elements (such as micro-lenses, prisms, and/ordiffractive elements) for beam shaping and/or beam steering of lightbeams used, for example, for eye tracking. In some examples, an opticalelement is fabricated directly on the emissive surface of a lightsource. The light source may be, for example, a light-emitting diode ora laser (e.g., a vertical cavity surface-emissive laser or VCSEL).Example high refractive index materials include semiconductors, such asarsenide semiconductors (e.g., GaAs, AlAs, AlGaAs), phosphidesemiconductors (e.g., GaP, InP, InGaP), nitride semiconductors (e.g.,InN, GaN, AIN, GaAIN, GaInN, etc.), other III-V or II-VI semiconductors,or inorganic dielectric materials such as oxides (e.g., titaniumdioxide). In some examples, the refractive index of the high-indexmaterial may be at least approximately 2, or at least approximately 3(e.g., at the light source emission wavelength and a typical operatingtemperature). In some examples, an optical element may include asemiconductor having a bandgap greater than the photon energy of lightfrom the light source. In some examples, an optical element may befabricated directly on the light source, for example, usingsemiconductor processing techniques. In some examples, an opticalelement may be fabricated on a separate substrate and placed on thelight source, for example, bonded with or without an adhesive. In someexamples, light sources and optical elements may be fabricated onseparate wafers, and the wafers then aligned and bonded. In someapplications, the light sources may be part of augmented or virtualreality headware, for example, LEDs embedded in the lenses of augmentedreality glasses. The optical elements may be used to direct a light beamtowards the center of the eyebox, for example, with an improved beamshape, improved illumination properties such as illumination uniformity,improved glint capture, and/or improved algorithmic pupil edgedetection. An optical element may have a complex surface shape, such asa freeform surface. In some examples, the optical element may have anoptical coating, for example, to modify reflection or diffractionproperties.

In some examples, an optical element may be a lens having a freeformcurved surface. The freeform surface may be represented by Equation 1,as follows:

$\begin{matrix}{z = {\frac{{cr}^{2}}{1 + \sqrt{1 - {( {1 + k} )c^{2}r^{2}}}} + {\sum\limits_{i = 1}^{N}{A_{i}{{E_{i}( {x,y} )}.}}}}} & ( {{Equation}\mspace{14mu} 1} )\end{matrix}$

In Equation 1 above, z represents the surface coordinate (e.g., relativeto a value representative of a planar surface, for example, relative toa plane at z=0, and this term may also be referred to as the sag), c isa constant (in some examples, c may be referred to as the curvature), ris a radial distance from the optic axis (e.g., a radial distance from acenter of the lens), and k is a constant (e.g., sometimes referred to asa conic constant). For the second term (on the right of the equalitysymbol), N may represent the order of the numerical representation(discussed further below), and A, and E, may represent coefficients,such as additional coefficients describing the surface form in powers ofx and/or y.

In some examples, the surface coordinate z, along a particulardirection, may be a function of a radial distance (r) from the opticaxis, and the second term in Equation 1 may be replaced by asphericcoefficients associated with powers of the radial distance, for example,aspheric coefficients of the form A,r′, where i may have one or morevalues, such as 1, 2, 3, 4, 5, 6, etc., A may be termed an asphericparameter, and r is a radial distance. However, the asphericcoefficients may also vary with a function of the direction along whichthe radial distance is measured.

In some examples, an aspheric surface may have rotational symmetry aboutthe optic axis. However, in some examples, an optical element may havean aspheric surface that lacks such rotational symmetry, that may betermed a freeform surface. A freeform surface may lack any rotationalsymmetry about the optic axis, and may lack any symmetry. In someexamples, a freeform surface may be described by one or morecoefficients (that may be termed freeform coefficients) related topowers of a distance (e.g., along a particular direction, such as alongorthogonal x or y directions) that may be different along the differentdirections. For example, a freeform surface may be represented by anequation having the form of Equation 1, and the coefficients A_(i) andE_(i) may be termed freeform coefficients.

A freeform surface may have coefficients representing surface variationsalong the x direction (e.g., associated with different powers ofdistance along the x direction), along the y direction (e.g., associatedwith different powers of distance along the y direction), and mayinclude coefficients that may be termed cross-terms, having both x and ydependencies (e.g., coefficients of terms in xy, xy², etc.). In someexamples, a surface of an optical element may be spherical or asphericalong a particular direction, and spherical or aspheric (e.g., with adifferent radius of curvature and/or different aspheric coefficients)along another direction (such as along an orthogonal direction). In someexamples, a device includes an optical element including an asphericsurface, such as a freeform surface, having at least one non-zero (e.g.,appreciable) value of one or more aspheric or freeform coefficients, forexample, along one or more directions orthogonal to the optic axis. Insome examples, a surface may be a freeform surface, having numericalfreeform coefficients associated with the dependency of the surfacecoordinate (e.g., z of Equation 1) on one or more powers of a distancefrom a reference point, for example, powers of distance measured alongorthogonal x and y directions. In some examples, a freeform surface maybe considered to be a type of aspheric surface, for example, an asphericsurface lacking symmetry. A freeform surface may lack any rotationalsymmetry around the optic axis, unlike a spherical surface.

In some examples, the freeform surface may be configured so that theefficiency of the eyebox illumination is at least 80%, and in someexamples, at least 90%. In some examples, the illumination is generallyuniform, for example, uniform within one standard deviation.

In some examples, the optical properties of a freeform surface may beobtained using a combination of a prismatic optical element, and ametamaterial layer. The oblique exit surface of the prismatic opticalelement may redirect the beam. Spatially-variable properties of ametamaterial layer may be used for beam shaping, and to obtain improvedillumination uniformity, compared with, for example, a prismatic opticalelement without a metamaterial layer.

In some examples, a control system may be used to provide one or more ofthe following functions: to control an image displayed by a head-mounteddevice, receive and analyze sensor data (e.g., receive and analyzereflected light detected by an optical sensor, such as eye glint, anddetermine eye track data), to adjust one or more adjustable lenses, orto control light sources (such as lasers and/or light-emitting diodes).In some examples, a control system may include a display system, and maybe used to adjust an image shown on a display. In some examples, acontrol system may be used to adjust the optical properties of one ormore optical elements, such as the focal length of a lens, theorientation of an optical element, the deformation of a film (such as anelectroactive film), or to adjust any other optical component or lightsource. In some examples, a control system may be used to adjust thelight output power of a light source, for example, in response toambient brightness, eye-tracking requirements of a particularapplication, the importance of an augmented reality or virtual realityimage element, or to achieve a user-controlled setting such as contrastratio or brightness.

FIG. 23 shows a schematic of an example control system for a near-eyedisplay system, such as an augmented reality system. The display system2300 may include a near-eye display (NED) 2310 and a control system2320, that may be communicatively coupled to each other. The near-eyedisplay 2310 may include lenses 2312, electroactive devices (such asactuators) 2314, displays 2316, and one or more sensors 2318. Sensorsmay include at least one light sensor. Control system 2320 may include acontrol element 2322, a force lookup table 2324, and augmented realitylogic 2326 generating image stream 2328.

Augmented reality logic 2326 may determine what virtual objects are tobe displayed and real-world positions onto which the virtual objects areto be projected. Augmented reality logic 2326 may generate an imagestream 2328 that is displayed by displays 2316 in such a way thatalignment of right- and left-side images displayed in displays 2316results in ocular vergence toward a desired real-world position.

The control element 2322 may be configured to control one or moreadjustable lenses, for example, a fluid lens located within a near-eyedisplay. Lens adjustment may be based on the desired perceived distanceto a virtual object (this may, for example, include augmented realityimage elements).

Control element 2322 may use the same positioning information determinedby augmented reality logic 2326, in combination with force lookup table(LUT) 2324, to determine an amount of force to be applied byelectroactive devices 2314 (e.g., actuators), as described herein, tolenses 2312. Electroactive devices 2314 may, responsive to controlelement 2322, apply appropriate forces to lenses 2312 to adjust theapparent accommodation distance of virtual images displayed in displays2316 to match the apparent vergence distance of the virtual images,thereby reducing or eliminating vergence-accommodation conflict. Controlelement 2322 may be in communication with sensor 2318, that may measurea state of the adjustable lens. Based on data received from sensor 2318,the control element 2322 may adjust electroactive devices 2314 (e.g., asa closed-loop control system).

In some embodiments, display system 2300 may display multiple virtualobjects at once and may determine which virtual object a user is viewing(or is likely to be viewing) to identify a virtual object for which tocorrect the apparent accommodation distance. For example, the system mayinclude an eye-tracking system (not shown) that provides information tocontrol element 2322, to enable control element 2322 to select theposition of the relevant virtual object.

Additionally or alternatively, augmented reality logic 2326 may provideinformation about which virtual object is the most important and/or mostlikely to draw the attention of the user (e.g., based on spatial ortemporal proximity, movement, and/or a semantic importance metricattached to the virtual object). In some embodiments, the augmentedreality logic 2326 may identify multiple potentially important virtualobjects and select an apparent accommodation distance that approximatesthe virtual distance of a group of the potentially important virtualobjects.

Control system 2320 may represent any suitable hardware, software, orcombination thereof for managing adjustments to lenses (e.g., adjustablelenses) 2312. In some embodiments, control system 2320 may represent asystem on a chip (SOC). As such, one or more portions of control system2320 may include one or more hardware modules. Additionally oralternatively, one or more portions of control system 2320 may includeone or more software modules that perform one or more of the tasksdescribed herein when stored in the memory of a computing device andexecuted by a hardware processor of the computing device.

Control system 2320 may generally represent any suitable system forproviding display data, augmented reality data, and/or augmented realitylogic fora head-mounted display. In some embodiments, a control system2320 may include a graphics processing unit (GPU) and/or any other typeof hardware accelerator designed to optimize graphics processing.

Control system 2320 may be implemented in various types of systems, suchas augmented reality glasses. A control system may be used to controloperation of one or more of a display, a light source, an adjustablelens, image rendering, sensor analysis, and the like. In someembodiments, a control system may be integrated into a frame of aneyewear device. Alternatively, all or a portion of control system may bein a system remote from the eyewear, and, for example, configured tocontrol electroactive devices (e.g., actuators), display components, orother optical components in the eyewear via wired or wirelesscommunication.

The control system, which in some examples may also be referred to as acontroller, may control the operations of the light source and, in somecases, the optics system, that may include control of one or morelenses. In some embodiments, the controller may be the graphicsprocessing unit (GPU) of a display device. In some embodiments, thecontroller may include one or more different or additional processors.The operations performed by the controller may include taking contentfor display and dividing the content into discrete sections. Thecontroller may instruct the light source to sequentially present thediscrete sections using light emitters corresponding to a respective rowin an image ultimately displayed to the user. The controller mayinstruct the optics system to adjust the light. For example, thecontroller may control the optics system to scan the presented discretesections to different areas of a coupling element of the light output.Each discrete portion may be presented in a different location at theexit pupil. While each discrete section is presented at different times,the presentation and scanning of the discrete sections may occur fastenough such that a user's eye integrates the different sections into asingle image or series of images. The controller may also providescanning instructions to the light source that include an addresscorresponding to an individual source element of the light source and/oran electrical bias applied to an individual source or display element.

An example control system (that may also be termed a controller) mayinclude an image processing unit. The controller, or component imageprocessing unit, may include a general-purpose processor and/or one ormore application-specific circuits that are dedicated to performing thefeatures described herein. In one embodiment, a general-purposeprocessor may be coupled to a memory device to execute softwareinstructions that cause the processor to perform certain processesdescribed herein. In some embodiments, the image processing unit mayinclude one or more circuits that are dedicated to performing certainfeatures. The image processing unit may be a stand-alone unit that isseparate from the controller and the driver circuit, but in someembodiments the image processing unit may be a sub-unit of thecontroller or the driver circuit. In other words, in those embodiments,the controller or the driver circuit performs various image processingprocedures of the image processing unit. The image processing unit mayalso be referred to as an image processing circuit.

Ophthalmic applications of the devices described herein may includespectacles with a flat front (or other curved) substrate and anadjustable eye-side concave or convex membrane surface. Applicationsinclude optics, augmented reality, or virtual reality headsets. Exampledevices may include head-mounted-display devices such as augmentedreality and/or virtual reality devices.

Embodiments of the present disclosure may include or be implemented inconjunction with various types of artificial reality systems. Artificialreality is a form of reality that has been adjusted in some mannerbefore presentation to a user, that may include, for example, a virtualreality, an augmented reality, a mixed reality, a hybrid reality, orsome combination and/or derivative thereof. Artificial-reality contentmay include completely computer-generated content or computer-generatedcontent combined with captured (e.g., real-world) content. Theartificial-reality content may include video, audio, haptic feedback, orsome combination thereof, any of that may be presented in a singlechannel or in multiple channels (such as stereo video that produces athree-dimensional (3D) effect to the viewer). Additionally, in someembodiments, artificial reality may also be associated withapplications, products, accessories, services, or some combinationthereof, that are used to, for example, create content in an artificialreality and/or are otherwise used in (e.g., to perform activities in) anartificial reality.

Artificial-reality systems may be implemented in a variety of differentform factors and configurations. Some artificial reality systems may bedesigned to work without near-eye displays (NEDs). Other artificialreality systems may include an NED that also provides visibility intothe real world (such as, e.g., augmented-reality system 2400 in FIG. 24)or that visually immerses a user in an artificial reality (such as,e.g., virtual-reality system 2500 in FIG. 25). While someartificial-reality devices may be self-contained systems, otherartificial-reality devices may communicate and/or coordinate withexternal devices to provide an artificial-reality experience to a user.Examples of such external devices include handheld controllers, mobiledevices, desktop computers, devices worn by a user, devices worn by oneor more other users, and/or any other suitable external system.

Turning to FIG. 24, augmented-reality system 2400 may include an eyeweardevice 2402 with a frame 2410 configured to hold a left display device2415(A) and a right display device 2415(B) in front of a user's eyes.Display devices 2415(A) and 2415(B) may act together or independently topresent an image or series of images to a user. While augmented-realitysystem 2400 includes two displays, embodiments of this disclosure may beimplemented in augmented-reality systems with a single NED or more thantwo NEDs.

In some embodiments, augmented-reality system 2400 may include one ormore sensors, such as sensor 2440. Sensor 2440 may generate measurementsignals in response to motion of augmented-reality system 2400 and maybe located on substantially any portion of frame 2410. Sensor 2440 mayrepresent one or more of a variety of different sensing mechanisms, suchas a position sensor, an inertial measurement unit (IMU), a depth cameraassembly, a structured light emitter and/or detector, a light sensor, orany combination thereof. In some examples, a light sensor may beconfigured to detect light reflected by the eye, such as light providedby a light source of an eye-tracking system. In some embodiments,augmented-reality system 2400 may or may not include sensor 2440 or mayinclude more than one sensor. In embodiments in which sensor 2440includes an IMU, the IMU may generate calibration data based onmeasurement signals from sensor 2440. Examples of sensor 2440 mayinclude, without limitation, accelerometers, gyroscopes, magnetometers,light sensors, other suitable types of sensors that detect motion,sensors used for error correction of the IMU, or some combinationthereof.

In some examples, augmented-reality system 2400 may also include amicrophone array with a plurality of acoustic transducers2420(A)-2420(J), referred to collectively as acoustic transducers 2420.Acoustic transducers 2420 may represent transducers that detect airpressure variations induced by sound waves. Each acoustic transducer2420 may be configured to detect sound and convert the detected soundinto an electronic format (e.g., an analog or digital format). Themicrophone array in FIG. 25 may include, for example, ten acoustictransducers: 2420(A) and 2420(B), that may be designed to be placedinside a corresponding ear of the user, acoustic transducers 2420(C),2420(D), 2420(E), 2420(F), 2420(G), and 2420(H), that may be positionedat various locations on frame 2410, and/or acoustic transducers 2420(I)and 2420(J), that may be positioned on a corresponding neckband 2405.

In some embodiments, one or more of acoustic transducers 2420(A)-(F) maybe used as output transducers (e.g., speakers). For example, acoustictransducers 2420(A) and/or 2420(B) may be earbuds or any other suitabletype of headphone or speaker.

The configuration of acoustic transducers 2420 of the microphone arraymay vary. While augmented-reality system 2400 is shown in FIG. 24 ashaving ten acoustic transducers 2420, the number of acoustic transducers2420 may be greater or less than ten. In some embodiments, using highernumbers of acoustic transducers 2420 may increase the amount of audioinformation collected and/or the sensitivity and accuracy of the audioinformation. In contrast, using a lower number of acoustic transducers2420 may decrease the computing power required by an associatedcontroller 2450 to process the collected audio information. In addition,the position of each acoustic transducer 2420 of the microphone arraymay vary. For example, the position of an acoustic transducer 2420 mayinclude a defined position on the user, a defined coordinate on frame2410, an orientation associated with each acoustic transducer 2420, orsome combination thereof.

Acoustic transducers 2420(A) and 2420(B) may be positioned on differentparts of the user's ear, such as behind the pinna, behind the tragus,and/or within the auricle or fossa. Or, there may be additional acoustictransducers 2420 on or surrounding the ear in addition to acoustictransducers 2420 inside the ear canal. Having an acoustic transducer2420 positioned next to an ear canal of a user may enable the microphonearray to collect information on how sounds arrive at the ear canal. Bypositioning at least two of acoustic transducers 2420 on either side ofa user's head (e.g., as binaural microphones), augmented-reality device2400 may simulate binaural hearing and capture a 3D stereo sound fieldaround about a user's head.

In some embodiments, acoustic transducers 2420(A) and 2420(B) may beconnected to augmented-reality system 2400 via a wired connection 2430,and in other embodiments acoustic transducers 2420(A) and 2420(B) may beconnected to augmented-reality system 2400 via a wireless connection(e.g., a Bluetooth connection). In still other embodiments, acoustictransducers 2420(A) and 2420(B) may not be used at all in conjunctionwith augmented-reality system 2400.

Acoustic transducers 2420 on frame 2410 may be positioned in a varietyof different ways, including along the length of the temples, across thebridge, above or below display devices 2415(A) and 2415(B), or somecombination thereof. Acoustic transducers 2420 may also be oriented suchthat the microphone array is able to detect sounds in a wide range ofdirections surrounding the user wearing the augmented-reality system2400. In some embodiments, an optimization process may be performedduring manufacturing of augmented-reality system 2400 to determinerelative positioning of each acoustic transducer 2420 in the microphonearray.

In some examples, augmented-reality system 2400 may include or beconnected to an external device (e.g., a paired device), such asneckband 2405. Neckband 2405 generally represents any type or form ofpaired device. Thus, the following discussion of neckband 2405 may alsoapply to various other paired devices, such as charging cases, smartwatches, smart phones, wrist bands, other wearable devices, hand-heldcontrollers, tablet computers, laptop computers, other external computedevices, etc.

As shown, neckband 2405 may be coupled to eyewear device 2402 via one ormore connectors. The connectors may be wired or wireless and may includeelectrical and/or non-electrical (e.g., structural) components. In somecases, eyewear device 2402 and neckband 2405 may operate independentlywithout any wired or wireless connection between them. While FIG. 24illustrates the components of eyewear device 2402 and neckband 2405 inexample locations on eyewear device 2402 and neckband 2405, thecomponents may be located elsewhere and/or distributed differently oneyewear device 2402 and/or neckband 2405. In some embodiments, thecomponents of eyewear device 2402 and neckband 2405 may be located onone or more additional peripheral devices paired with eyewear device2402, neckband 2405, or some combination thereof.

Pairing external devices, such as neckband 2405, with augmented-realityeyewear devices may enable the eyewear devices to achieve the formfactor of a pair of glasses while still providing sufficient battery andcomputation power for expanded capabilities. Some or all of the batterypower, computational resources, and/or additional features ofaugmented-reality system 2400 may be provided by a paired device orshared between a paired device and an eyewear device, thus reducing theweight, heat profile, and form factor of the eyewear device overallwhile still retaining desired functionality. For example, neckband 2405may allow components that would otherwise be included on an eyeweardevice to be included in neckband 2405 since users may tolerate aheavier weight load on their shoulders than they would tolerate on theirheads. Neckband 2405 may also have a larger surface area over which todiffuse and disperse heat to the ambient environment. Thus, neckband2405 may allow for greater battery and computation capacity than mightotherwise have been possible on a stand-alone eyewear device. Sinceweight carried in neckband 2405 may be less invasive to a user thanweight carried in eyewear device 2402, a user may tolerate wearing alighter eyewear device and carrying or wearing the paired device forgreater lengths of time than a user would tolerate wearing a heavystandalone eyewear device, thereby enabling users to more fullyincorporate artificial reality environments into their day-to-dayactivities.

Neckband 2405 may be communicatively coupled with eyewear device 2402and/or to other devices. These other devices may provide certainfunctions (e.g., tracking, localizing, depth mapping, processing,storage, etc.) to augmented-reality system 2400. In the embodiment ofFIG. 24, neckband 2405 may include two acoustic transducers (e.g.,2420(I) and 2420(J)) that are part of the microphone array (orpotentially form their own microphone subarray). Neckband 2405 may alsoinclude a controller 2425 and a power source 2435.

Acoustic transducers 2420(I) and 2420(J) of neckband 2405 may beconfigured to detect sound and convert the detected sound into anelectronic format (analog or digital). In the embodiment of FIG. 24,acoustic transducers 2420(I) and 2420(J) may be positioned on neckband2405, thereby increasing the distance between the neckband acoustictransducers 2420(I) and 2420(J) and other acoustic transducers 2420positioned on eyewear device 2402. In some cases, increasing thedistance between acoustic transducers 2420 of the microphone array mayimprove the accuracy of beamforming performed via the microphone array.For example, if a sound is detected by acoustic transducers 2420(C) and2420(D) and the distance between acoustic transducers 2420(C) and2420(D) is greater than, for example, the distance between acoustictransducers 2420(D) and 2420(E), the determined source location of thedetected sound may be more accurate than if the sound had been detectedby acoustic transducers 2420(D) and 2420(E).

Controller 2425 of neckband 2405 may process information generated bythe sensors on neckband 2405 and/or augmented-reality system 2400. Forexample, controller 2425 may process information from the microphonearray that describes sounds detected by the microphone array. For eachdetected sound, controller 2425 may perform a direction-of-arrival (DOA)estimation to estimate a direction from which the detected sound arrivedat the microphone array. As the microphone array detects sounds,controller 2425 may populate an audio data set with the information. Inembodiments in which augmented-reality system 2400 includes an inertialmeasurement unit, controller 2425 may compute all inertial and spatialcalculations from the IMU located on eyewear device 2402. A connectormay convey information between augmented-reality system 2400 andneckband 2405 and between augmented-reality system 2400 and controller2425. The information may be in the form of optical data, electricaldata, wireless data, or any other transmittable data form. Moving theprocessing of information generated by augmented-reality system 2400 toneckband 2405 may reduce weight and heat in eyewear device 2402, makingit more comfortable to the user.

Power source 2435 in neckband 2405 may provide power to eyewear device2402 and/or to neckband 2405. Power source 2435 may include, withoutlimitation, lithium ion batteries, lithium-polymer batteries, primarylithium batteries, alkaline batteries, or any other form of powerstorage. In some cases, power source 2435 may be a wired power source.Including power source 2435 on neckband 2405 instead of on eyeweardevice 2402 may help better distribute the weight and heat generated bypower source 2435.

As noted, some artificial reality systems may, instead of blending anartificial reality with actual reality, substantially replace one ormore of a user's sensory perceptions of the real world with a virtualexperience. One example of this type of system is a head-worn displaysystem, such as virtual-reality system 2500 in FIG. 25, that mostly orcompletely covers a user's field of view. Virtual-reality system 2500may include a front rigid body 2502 and a band 2504 shaped to fit arounda user's head. Virtual-reality system 2500 may also include output audiotransducers 2506(A) and 2506(B). Furthermore, while not shown in FIG.25, front rigid body 2502 may include one or more electronic elements,including one or more electronic displays, one or more inertialmeasurement units (IMUs), one or more tracking emitters or detectors,and/or any other suitable device or system for creating anartificial-reality experience.

Artificial reality systems may include a variety of types of visualfeedback mechanisms. For example, display devices in augmented-realitysystem 2400 and/or virtual-reality system 2500 may include one or moreliquid crystal displays (LCDs), light-emitting diode (LED) displays,organic LED (OLED) displays, digital light project (DLP) micro-displays,liquid crystal on silicon (LCoS) micro-displays, and/or any othersuitable type of display screen. These artificial reality systems mayinclude a single display screen for both eyes or may provide a displayscreen for each eye, that may allow for additional flexibility forvarifocal adjustments or for correcting a user's refractive error. Someof these artificial reality systems may also include optical subsystemshaving one or more lenses (e.g., conventional concave or convex lenses,Fresnel lenses, adjustable liquid lenses, etc.) through which a user mayview a display screen. These optical subsystems may serve a variety ofpurposes, including to collimate (e.g., make an object appear at agreater distance than its physical distance), to magnify (e.g., make anobject appear larger than its actual size), and/or to relay (to, e.g.,the viewer's eyes) light. These optical subsystems may be used in anon-pupil-forming architecture (such as a single lens configuration thatdirectly collimates light but results in so-called pincushiondistortion) and/or a pupil-forming architecture (such as a multi-lensconfiguration that produces so-called barrel distortion to nullifypincushion distortion).

In addition to or instead of using display screens, some the artificialreality systems described herein may include one or more projectionsystems. For example, display devices in augmented-reality system 2400and/or virtual-reality system 2500 may include micro-LED projectors thatproject light (using, e.g., a waveguide) into display devices, such asclear combiner lenses that allow ambient light to pass through. Thedisplay devices may refract the projected light toward a user's pupiland may enable a user to simultaneously view both artificial realitycontent and the real world. The display devices may accomplish thisusing any of a variety of different optical components, includingwaveguide components (e.g., holographic, planar, diffractive, polarized,and/or reflective waveguide elements), light-manipulation surfaces andelements (such as diffractive, reflective, and refractive elements andgratings), coupling elements, etc. Artificial reality systems may alsobe configured with any other suitable type or form of image projectionsystem, such as retinal projectors used in virtual retina displays.

The artificial reality systems described herein may also include varioustypes of computer vision components and subsystems. For example,augmented-reality system 2400 and/or virtual-reality system 2500 mayinclude one or more optical sensors (which may also be termed lightsensors), such as two-dimensional (2D) or 3D cameras, structured lighttransmitters and detectors, time-of-flight depth sensors, single-beam orsweeping laser rangefinders, 3D LiDAR sensors, and/or any other suitabletype or form of optical sensor. An artificial reality system may processdata from one or more of these sensors to identify a location of a user,to map the real world, to provide a user with context about real-worldsurroundings, and/or to perform a variety of other functions.

The artificial reality systems described herein may also include one ormore input and/or output audio transducers. Output audio transducers mayinclude voice coil speakers, ribbon speakers, electrostatic speakers,piezoelectric speakers, bone conduction transducers, cartilageconduction transducers, tragus-vibration transducers, and/or any othersuitable type or form of audio transducer. Similarly, input audiotransducers may include condenser microphones, dynamic microphones,ribbon microphones, and/or any other type or form of input transducer.In some embodiments, a single transducer may be used for both audioinput and audio output.

In some embodiments, the artificial reality systems described herein mayalso include tactile (i.e., haptic) feedback systems, that may beincorporated into headwear, gloves, body suits, handheld controllers,environmental devices (e.g., chairs, floormats, etc.), and/or any othertype of device or system. Haptic feedback systems may provide varioustypes of cutaneous feedback, including vibration, force, traction,texture, and/or temperature. Haptic feedback systems may also providevarious types of kinesthetic feedback, such as motion and compliance.Haptic feedback may be implemented using motors, piezoelectricactuators, fluidic systems, and/or a variety of other types of feedbackmechanisms. Haptic feedback systems may be implemented independent ofother artificial reality devices, within other artificial realitydevices, and/or in conjunction with other artificial reality devices.

By providing haptic sensations, audible content, and/or visual content,artificial reality systems may create an entire virtual experience orenhance a user's real-world experience in a variety of contexts andenvironments. For instance, artificial reality systems may assist orextend a user's perception, memory, or cognition within a particularenvironment. Some systems may enhance a user's interactions with otherpeople in the real world or may enable more immersive interactions withother people in a virtual world. Artificial reality systems may also beused for educational purposes (e.g., for teaching or training inschools, hospitals, government organizations, military organizations,business enterprises, etc.), entertainment purposes (e.g., for playingvideo games, listening to music, watching video content, etc.), and/orfor accessibility purposes (e.g., as hearing aids, visual aids, etc.).The embodiments disclosed herein may enable or enhance a user'sartificial reality experience in one or more of these contexts andenvironments and/or in other contexts and environments.

In some embodiments, the systems described herein may also include aneye-tracking subsystem designed to identify and track variouscharacteristics of a user's eye(s), such as the user's gaze direction.The phrase “eye tracking” may, in some examples, refer to a process bywhich the position, orientation, and/or motion of an eye is measured,detected, sensed, determined, and/or monitored. The disclosed systemsmay measure the position, orientation, and/or motion of an eye in avariety of different ways, including through the use of variousoptical-based eye-tracking techniques, ultrasound-based eye-trackingtechniques, etc. An eye-tracking subsystem may be configured in a numberof different ways and may include a variety of different eye-trackinghardware components or other computer-vision components. For example, aneye-tracking subsystem may include a variety of different opticalsensors, such as two-dimensional (2D) or 3D cameras, time-of-flightdepth sensors, single-beam or sweeping laser rangefinders, 3D LiDARsensors, and/or any other suitable type or form of optical sensor. Inthis example, a processing subsystem may process data from one or moreof these sensors to measure, detect, determine, and/or otherwise monitorthe position, orientation, and/or motion of the user's eye(s). Opticalsensors may also be referred to as light sensors.

FIG. 26 is an illustration of an exemplary system 2600 that incorporatesan eye-tracking subsystem capable of tracking a user's eye(s). Asdepicted in FIG. 26, system 2600 may include a light source 2602, anoptical subsystem 2604, an eye-tracking subsystem 2606, and/or a controlsubsystem 2608. In some examples, light source 2602 may generate lightfor an image (e.g., to be presented to an eye 2601 of the viewer). Lightsource 2602 may represent any of a variety of suitable devices. Forexample, light source 2602 can include a two-dimensional projector(e.g., a LCoS display), a scanning source (e.g., a scanning laser), orother device (e.g., an LCD, an LED display, an OLED display, anactive-matrix OLED display (AMOLED), a transparent OLED display (TOLED),a waveguide, or some other display capable of generating light forpresenting an image to the viewer). In some examples, the image mayrepresent a virtual image, that may refer to an optical image formedfrom the apparent divergence of light rays from a point in space, asopposed to an image formed from the light ray's actual divergence.

In some embodiments, optical subsystem 2604 may receive the lightgenerated by light source 2602 and generate, based on the receivedlight, converging light 2620 that includes the image. In some examples,optical subsystem 2604 may include any number of lenses (e.g., Fresnellenses, convex lenses, concave lenses), apertures, filters, mirrors,prisms, and/or other optical components, possibly in combination withactuators and/or other devices. In particular, the actuators and/orother devices may translate and/or rotate one or more of the opticalcomponents to alter one or more aspects of converging light 2620.Further, various mechanical couplings may serve to maintain the relativespacing and/or the orientation of the optical components in any suitablecombination.

In one embodiment, eye-tracking subsystem 2606 may generate trackinginformation indicating a gaze angle of an eye 2601 of the viewer. Inthis embodiment, control subsystem 2608 may control aspects of opticalsubsystem 2604 (e.g., the angle of incidence of converging light 2620)based at least in part on this tracking information. Additionally, insome examples, control subsystem 2608 may store and utilize historicaltracking information (e.g., a history of the tracking information over agiven duration, such as the previous second or fraction thereof) toanticipate the gaze angle of eye 2601 (e.g., an angle between the visualaxis and the anatomical axis of eye 2601). In some embodiments,eye-tracking subsystem 2606 may detect radiation emanating from someportion of eye 2601 (e.g., the cornea, the iris, the pupil, or the like)to determine the current gaze angle of eye 2601. In other examples,eye-tracking subsystem 2606 may employ a wavefront sensor to track thecurrent location of the pupil.

Any number of techniques can be used to track eye 2601. Some techniquesmay involve illuminating eye 2601 with infrared light and measuringreflections with at least one optical sensor that is tuned to besensitive to the infrared light. Information about how the infraredlight is reflected from eye 2601 may be analyzed to determine theposition(s), orientation(s), and/or motion(s) of one or more eyefeature(s), such as the cornea, pupil, iris, and/or retinal bloodvessels.

In some examples, the radiation captured by a light sensor ofeye-tracking subsystem 2606 may be digitized (i.e., converted to anelectronic signal). Further, the sensor may transmit a digitalrepresentation of this electronic signal to one or more processors(e.g., processors associated with a device including eye-trackingsubsystem 2606). Eye-tracking subsystem 2606 may include any of avariety of sensors in a variety of different configurations. Forexample, eye-tracking subsystem 2606 may include an infrared detectorthat reacts to infrared radiation. The infrared detector may be athermal detector, a photonic detector, and/or any other suitable type ofdetector. Thermal detectors may include detectors that react to thermaleffects of the incident infrared radiation.

In some examples, one or more processors may process the digitalrepresentation generated by the sensor(s) of eye-tracking subsystem 2606to track the movement of eye 2601. In another example, these processorsmay track the movements of eye 2601 by executing algorithms representedby computer-executable instructions stored on non-transitory memory. Insome examples, on-chip logic (e.g., an application-specific integratedcircuit or ASIC) may be used to perform at least portions of suchalgorithms. As noted, eye-tracking subsystem 2606 may be programmed touse an output of the sensor(s) to track movement of eye 2601. In someembodiments, eye-tracking subsystem 2606 may analyze the digitalrepresentation generated by the sensors to extract eye rotationinformation from changes in reflections. In one embodiment, eye-trackingsubsystem 2606 may use corneal reflections or glints (also known asPurkinje images) and/or the center of the eye's pupil 2622 as featuresto track over time.

In some embodiments, eye-tracking subsystem 2606 may use the center ofthe eye's pupil 2622 and infrared or near-infrared, non-collimated lightto create corneal reflections. In these embodiments, eye-trackingsubsystem 2606 may use the vector between the center of the eye's pupil2622 and the corneal reflections to compute the gaze direction of eye2601. In some embodiments, the disclosed systems may perform acalibration procedure for an individual (using, e.g., supervised orunsupervised techniques) before tracking the user's eyes. For example,the calibration procedure may include directing users to look at one ormore points displayed on a display while the eye-tracking system recordsthe values that correspond to each gaze position associated with eachpoint.

In some embodiments, eye-tracking subsystem 2606 may use two types ofinfrared and/or near-infrared (also known as active light) eye-trackingtechniques: bright-pupil and dark-pupil eye tracking, that may bedifferentiated based on the location of an illumination source withrespect to the optical elements used. If the illumination is coaxialwith the optical path, then eye 2601 may act as a retroreflector as thelight reflects off the retina, thereby creating a bright pupil effectsimilar to a red-eye effect in photography. If the illumination sourceis offset from the optical path, then the eye's pupil 2622 may appeardark because the retroreflection from the retina is directed away fromthe sensor. In some embodiments, bright-pupil tracking may creategreater iris/pupil contrast, allowing more robust eye tracking with irispigmentation, and may feature reduced interference (e.g., interferencecaused by eyelashes and other obscuring features). Bright-pupil trackingmay also allow tracking in lighting conditions ranging from totaldarkness to a very bright environment.

In some embodiments, control subsystem 2608 may control light source2602 and/or optical subsystem 2604 to reduce optical aberrations (e.g.,chromatic aberrations and/or monochromatic aberrations) of the imagethat may be caused by or influenced by eye 2601. In some examples, asmentioned above, control subsystem 2608 may use the tracking informationfrom eye-tracking subsystem 2606 to perform such control. For example,in controlling light source 2602, control subsystem 2608 may alter thelight generated by light source 2602 (e.g., by way of image rendering)to modify (e.g., pre-distort) the image so that the aberration of theimage caused by eye 2601 is reduced.

The disclosed systems may track both the position and relative size ofthe pupil (since, e.g., the pupil dilates and/or contracts). In someexamples, the eye-tracking devices and components (e.g., sensors and/orsources) used for detecting and/or tracking the pupil may be different(or calibrated differently) for different types of eyes. For example,the frequency range of the sensors may be different (or separatelycalibrated) for eyes of different colors and/or different pupil types,sizes, and/or the like. As such, the various eye-tracking components(e.g., infrared sources and/or sensors) described herein may need to becalibrated for each individual user and/or eye.

The disclosed systems may track both eyes with and without ophthalmiccorrection, such as that provided by contact lenses worn by the user. Insome embodiments, ophthalmic correction elements (e.g., adjustablelenses) may be directly incorporated into the artificial reality systemsdescribed herein. In some examples, the color of the user's eye maynecessitate modification of a corresponding eye-tracking algorithm. Forexample, eye-tracking algorithms may need to be modified based at leastin part on the differing color contrast between a brown eye and, forexample, a blue eye.

FIGS. 27A-B show a more detailed illustration of various aspects of theeye-tracking subsystem illustrated in FIG. 26. As shown in FIG. 27A, aneye-tracking subsystem 2700 may include at least one source 2704 and atleast one sensor 2706. Source 2704, which may include a light source,optical element, and encapsulant layer, may generally represents anytype or form of element capable of emitting radiation. In some examples,source 2704 may generate visible, infrared, and/or near-infraredradiation. In some examples, source 2704 may radiate non-collimatedinfrared and/or near-infrared portions of the electromagnetic spectrumtowards an eye 2702 of a user. Source 2704 may utilize a variety ofsampling rates and speeds. For example, the disclosed systems may usesources with higher sampling rates in order to capture fixational eyemovements of a user's eye 2702 and/or to correctly measure saccadedynamics of the user's eye 2702. As noted above, any type or form ofeye-tracking technique may be used to track the user's eye 2702,including optical-based eye-tracking techniques, ultrasound-basedeye-tracking techniques, etc.

Sensor 2706 generally represents any type or form of element capable ofdetecting radiation, such as radiation reflected off the user's eye2702. Examples of sensor 2706 include, without limitation, a chargecoupled device (CCD), a photodiode array, a complementarymetal-oxide-semiconductor (CMOS) based sensor device, and/or the like.In some examples, sensor 2706 may represent a sensor havingpredetermined parameters, including, but not limited to, a dynamicresolution range, linearity, and/or other characteristic selected and/ordesigned specifically for eye tracking.

As detailed above, eye-tracking subsystem 2700 may generate one or moreglints. As detailed above, a glint 2703 may represent reflections ofradiation (e.g., infrared radiation from an infrared source, such assource 2704) from the structure of the user's eye. In variousembodiments, glint 2703 and/or the user's pupil may be tracked using aneye-tracking algorithm executed by a processor (either within orexternal to an artificial reality device). For example, an artificialreality device may include a processor and/or a memory device in orderto perform eye tracking locally and/or a transceiver to send and receivethe data necessary to perform eye tracking on an external device (e.g.,a mobile phone, cloud server, or other computing device).

FIG. 27B shows an example image 2705 captured by an eye-trackingsubsystem, such as eye-tracking subsystem 2700. In this example, image2705 may include both the user's pupil 2708 and a glint 2710 near thesame. In some examples, pupil 2708 and/or glint 2710 may be identifiedusing an artificial-intelligence-based algorithm, such as acomputer-vision-based algorithm. In one embodiment, image 2705 mayrepresent a single frame in a series of frames that may be analyzedcontinuously in order to track the eye 2702 of the user. Further, pupil2708 and/or glint 2710 may be tracked over a period of time to determinea user's gaze.

In some examples, eye-tracking subsystem 2700 may be configured toidentify and measure the inter-pupillary distance (IPD) of a user. Insome embodiments, eye-tracking subsystem 2700 may measure and/orcalculate the IPD of the user while the user is wearing the artificialreality system. In these embodiments, eye-tracking subsystem 2700 maydetect the positions of a user's eyes and may use this information tocalculate the user's IPD.

As noted, the eye-tracking systems or subsystems disclosed herein maytrack a user's eye position and/or eye movement in a variety of ways. Insome examples, one or more light sources and/or optical sensors maycapture an image of the user's eyes. The eye-tracking subsystem may thenuse the captured information to determine the user's inter-pupillarydistance, interocular distance, and/or a 3D position of each eye (e.g.,for distortion adjustment purposes), including a magnitude of torsionand rotation (i.e., roll, pitch, and yaw) and/or gaze directions foreach eye. In some examples, infrared light may be emitted by theeye-tracking subsystem and reflected from each eye. The reflected lightmay be received or detected by an optical sensor and analyzed to extracteye rotation data from changes in the infrared light reflected by eacheye.

The eye-tracking subsystem may use any of a variety of different methodsto track the eyes of a user. For example, a light source (e.g., infraredlight-emitting diodes) may emit a dot pattern onto each eye of the user.The eye-tracking subsystem may then detect (e.g., via an optical sensorcoupled to the artificial reality system) and analyze a reflection ofthe dot pattern from each eye of the user to identify a location of eachpupil of the user. Accordingly, the eye-tracking subsystem may track upto six degrees of freedom of each eye (i.e., 3D position, roll, pitch,and yaw) and at least a subset of the tracked quantities may be combinedfrom two eyes of a user to estimate a gaze point (i.e., a 3D location orposition in a virtual scene where the user is looking) and/or an IPD.

In some cases, the distance between a user's pupil and a display maychange as the user's eye moves to look in different directions. Thevarying distance between a pupil and a display as viewing directionchanges may be referred to as “pupil swim” and may contribute todistortion perceived by the user as a result of light focusing indifferent locations as the distance between the pupil and the displaychanges. Accordingly, measuring distortion at different eye positionsand pupil distances relative to displays and generating distortioncorrections for different positions and distances may allow mitigationof distortion caused by pupil swim by tracking the 3D position of auser's eyes and applying a distortion correction corresponding to the 3Dposition of each of the user's eyes at a given point in time. Thus,knowing the 3D position of each of a user's eyes may allow for themitigation of distortion caused by changes in the distance between thepupil of the eye and the display by applying a distortion correction foreach 3D eye position. Furthermore, as noted above, knowing the positionof each of the user's eyes may also enable the eye-tracking subsystem tomake automated adjustments for a user's IPD.

In some embodiments, a display subsystem may include a variety ofadditional subsystems that may work in conjunction with the eye-trackingsubsystems described herein. For example, a display subsystem mayinclude a varifocal subsystem, a scene-rendering module, and/or avergence-processing module. The varifocal subsystem may cause left andright display elements to vary the focal distance of the display device.In one embodiment, the varifocal subsystem may physically change thedistance between a display and the optics through which it is viewed bymoving the display, the optics, or both. Additionally, moving ortranslating two lenses relative to each other may also be used to changethe focal distance of the display. Thus, the varifocal subsystem mayinclude actuators or motors that move displays and/or optics to changethe distance between them. This varifocal subsystem may be separate fromor integrated into the display subsystem. The varifocal subsystem mayalso be integrated into or separate from its actuation subsystem and/orthe eye-tracking subsystems described herein.

In some examples, the display subsystem may include avergence-processing module configured to determine a vergence depth of auser's gaze based on a gaze point and/or an estimated intersection ofthe gaze lines determined by the eye-tracking subsystem. Vergence mayrefer to the simultaneous movement or rotation of both eyes in oppositedirections to maintain single binocular vision, that may be naturallyand automatically performed by the human eye. Thus, a location where auser's eyes are verged is where the user is looking and is alsotypically the location where the user's eyes are focused. For example,the vergence-processing module may triangulate gaze lines to estimate adistance or depth from the user associated with intersection of the gazelines. The depth associated with intersection of the gaze lines may thenbe used as an approximation for the accommodation distance, that mayidentify a distance from the user where the user's eyes are directed.Thus, the vergence distance may allow for the determination of alocation where the user's eyes may be focused, and a depth from theuser's eyes at which the eyes are focused, thereby providing information(such as an object or plane of focus) for rendering adjustments to thevirtual scene.

The vergence-processing module may coordinate with the eye-trackingsubsystems described herein to make adjustments to the display subsystemto account for a user's vergence depth. When the user is focused onsomething at a distance, the user's pupils may be slightly farther apartthan when the user is focused on something close. The eye-trackingsubsystem may obtain information about the user's vergence or focusdepth and may adjust the display subsystem to be closer together whenthe user's eyes focus or verge on something close and to be fartherapart when the user's eyes focus or verge on something at a distance.

The eye-tracking information generated by the above-describedeye-tracking subsystems may also be used, for example, to modify variousaspect of how different computer-generated images are presented. Forexample, a display subsystem may be configured to modify, based oninformation generated by an eye-tracking subsystem, at least one aspectof how the computer-generated images are presented. For instance, thecomputer-generated images may be modified based on the user's eyemovement, such that if a user is looking up, the computer-generatedimages may be moved upward on the screen. Similarly, if the user islooking to the side or down, the computer-generated images may be movedto the side or downward on the screen. lithe user's eyes are closed, thecomputer-generated images may be paused or removed from the display andresumed once the user's eyes are back open.

The above-described eye-tracking subsystems can be incorporated into oneor more of the various artificial reality systems described herein in avariety of ways. For example, one or more of the various components ofsystem 2600 and/or eye-tracking subsystem 2700 may be incorporated intoaugmented-reality system 2400 in FIG. 24 and/or virtual-reality system2500 in FIG. 25 to enable these systems to perform various eye-trackingtasks (including one or more of the eye-tracking operations describedherein).

EXAMPLE EMBODIMENTS

Example 1. A device may include a light source configured to emit alight beam through a light-emissive surface of the light source, and anoptical element supported by the light-emissive surface, and configuredto receive the light beam along a first direction and redirect the lightbeam along a second direction, where the second direction is differentto the first direction, the optical element includes a material having arefractive index of greater than 2 at the wavelength of the light beam.

Example 2. The device of example 1, where the light source and opticalelement are integrated into a monolithic light-emitting module.

Example 3. The device of examples 1 or 2, where the material includes asemiconductor.

Example 4. The device of any of examples 1-3, where the semiconductorincludes an arsenide semiconductor, a phosphide semiconductor, or anitride semiconductor.

Example 5. The device of any of examples 1-4, where the light sourceincludes a laser.

Example 6. The device of any of examples 1-5, where the laser is avertical cavity surface-emissive laser.

Example 7. The device of any of examples 1-6, where the optical elementis formed on the light emissive surface of the laser.

Example 8. The device of any of examples 1-7, where the device is ahead-mounted device, and the device is configured to illuminate an eyeof a user using the light beam.

Example 9. The device of any of examples 1-8, where the device furtherincludes a light sensor configured to detect a reflection of the lightbeam from the eye.

Example 10. The device of any of examples 1-9, where the device is anaugmented reality device or a virtual reality device.

Example 11. The device of any of examples 1-10, where the opticalelement includes a metamaterial layer.

Example 12. The device of example 10, where the metamaterial layerincludes an arrangement of nanostructures.

Example 13. The device of any of examples 10-11, where thenanostructures each have a nanostructure parameter, where thenanostructure parameter has a spatial variation as a function ofposition within the metamaterial layer, and the spatial variation isconfigured to improve the illumination uniformity of a targetilluminated by the light beam.

Example 14. The device of any of examples 10-13, where the nanostructureparameter includes one or more of: a lateral dimension, across-sectional area, a length dimension, a composition, a nanostructurespacing, a cross-sectional shape, a cross-sectional shape anisotropy, across-sectional uniformity, a taper, a refractive index, a refractiveindex anisotropy, a coating thickness, a hollow core thickness, a volumefraction of at least one component, or an orientation.

Example 15. The device of any of examples 10-14, where thenanostructures include nanopillars, the nanopillars have a diameter, andthe nanostructure parameter is a nanopillar diameter.

Example 16. The device of any of examples 10-14, where thenanostructures include polarization-sensitive nanostructures.

Example 17. A method, including fabricating a laser having an emissivesurface, forming a layer on the emissive surface of the laser, forming aresist layer on the layer, the resist layer having a shape determined bya spatially non-uniform thickness of the resist layer, and etching theshape of the resist layer into the layer to form an optical elementhaving a shaped exit surface, where the optical element is supported bythe emissive surface of the surface-emissive laser, receives light fromthe surface-emissive laser, and is configured to redirect the light byrefraction through the shaped exit surface to illuminate a remotetarget.

Example 18. The method of example 17, where the shaped exit surface isan oblique surface, and the optical element includes a prism.

Example 19. The method of any of examples 17-18, where the shaped exitsurface includes a curved exit surface.

Example 20. The method of any of examples 17-19, where forming the layeron the emissive surface of the laser includes forming a passivationlayer on the emissive surface, and then forming the layer on thepassivation layer.

As detailed above, the devices and systems described and/or illustratedherein may broadly include any type or form of computing device orsystem capable of executing computer-readable instructions, such asthose contained within the modules described herein. In someconfigurations, these device(s) may include at least one memory deviceand at least one physical processor.

In some examples, the term “memory device” generally refers to any typeor form of volatile or non-volatile storage device or medium capable ofstoring data and/or computer-readable instructions. In some examples, amemory device may store, load, and/or maintain one or more of themodules described herein. Examples of memory devices include, withoutlimitation, Random Access Memory (RAM), Read Only Memory (ROM), flashmemory, Hard Disk Drives (HDDs), Solid-State Drives (SSDs), optical diskdrives, caches, variations or combinations of one or more of the same,or any other suitable storage memory.

In some examples, the term “physical processor” generally refers to anytype or form of hardware-implemented processing unit capable ofinterpreting and/or executing computer-readable instructions. In someexamples, a physical processor may access and/or modify one or moremodules stored in the above-described memory device. Examples ofphysical processors include, without limitation, microprocessors,microcontrollers, Central Processing Units (CPUs), Field-ProgrammableGate Arrays (FPGAs) that implement softcore processors,Application-Specific Integrated Circuits (ASICs), portions of one ormore of the same, variations or combinations of one or more of the same,or any other suitable physical processor.

Although discussed as separate elements, example modules describedand/or illustrated herein may represent portions of a single module orapplication. In addition, in certain embodiments one or more of thesemodules may represent one or more software applications or programsthat, when executed by a computing device, may cause the computingdevice to perform one or more tasks. For example, one or more of themodules described and/or illustrated herein may represent modules storedand configured to run on one or more of the computing devices or systemsdescribed and/or illustrated herein. One or more of these modules mayalso represent all or portions of one or more special-purpose computersconfigured to perform one or more tasks.

In addition, one or more of the modules described herein may transformdata, physical devices, and/or representations of physical devices fromone form to another. For example, one or more of the modules recitedherein may receive data to be transformed, transform the data, output aresult of the transformation to perform a function, use the result ofthe transformation to perform a function, and store the result of thetransformation to perform a function. Additionally or alternatively, oneor more of the modules recited herein may transform a processor,volatile memory, non-volatile memory, and/or any other portion of aphysical computing device from one form to another by executing on thecomputing device, storing data on the computing device, and/or otherwiseinteracting with the computing device. In some examples, data mayinclude configuration data related one or both of the user's eye(s)(e.g., external surface profile the cornea, lens focus, gaze direction,gaze time, gaze trajectory, eye accommodation data, pupil diameter,and/or eye vergence data).

In some embodiments, the term “computer-readable medium” may generallyrefer to any form of device, carrier, or medium capable of storing orcarrying computer-readable instructions. Examples of computer-readablemedia include, without limitation, transmission-type media, such ascarrier waves, and non-transitory-type media, such as magnetic-storagemedia (e.g., hard disk drives, tape drives, and floppy disks),optical-storage media (e.g., Compact Disks (CDs), Digital Video Disks(DVDs), and BLU-RAY disks), electronic-storage media (e.g., solid-statedrives and flash media), and other distribution systems.

The process parameters and sequence of the steps described and/orillustrated herein are given by way of example only and can be varied asdesired. For example, while the steps illustrated and/or describedherein may be shown or discussed in a particular order, these steps donot necessarily need to be performed in the order illustrated ordiscussed. The various exemplary methods described and/or illustratedherein may also omit one or more of the steps described or illustratedherein or include additional steps in addition to those disclosed.

The disclosures of the following US Applications are incorporated, intheir entirety, by this reference: U.S. Provisional Application Nos.62/803,001 and 62/802,995, both filed 8th Feb. 2019, U.S. ProvisionalApplication No. 62/841,728, filed 1st May 2019, and U.S. applicationSer. No. 16/720,024, filed 19th Dec. 2019.

Unless otherwise noted, the terms “connected to” and “coupled to” (andtheir derivatives), as used in the specification and claims, are to beconstrued as permitting both direct and indirect (i.e., via otherelements or components) connection. In addition, the terms “a” or “an,”as used in the specification and claims, are to be construed as meaning“at least one of.” Finally, for ease of use, the terms “including” and“having” (and their derivatives), as used in the specification andclaims, are interchangeable with and have the same meaning as the word“comprising.”

The preceding description has been provided to enable others skilled inthe art to best utilize various aspects of the exemplary embodimentsdisclosed herein. This exemplary description is not intended to beexhaustive or to be limited to any precise form disclosed. Manymodifications and variations are possible without departing from thespirit and scope of the present disclosure. The embodiments disclosedherein should be considered in all respects illustrative and notrestrictive. Reference should be made to the appended claims and theirequivalents in determining the scope of the present disclosure.

What is claimed is:
 1. A device, comprising: a light source configuredto emit a light beam through a light-emissive surface; and an opticalelement supported by the light-emissive surface and configured toreceive the light beam along a first direction and redirect the lightbeam along a second direction, wherein: the second direction isdifferent from the first direction; and the optical element comprises amaterial that has a refractive index of greater than 2 at a wavelengthof the light beam.
 2. The device of claim 1, wherein the light sourceand the optical element are integrated into a monolithic light-emittingmodule.
 3. The device of claim 1, wherein the material comprises asemiconductor.
 4. The device of claim 1, wherein the material comprisesat least one of an arsenide semiconductor, a phosphide semiconductor, ora nitride semiconductor.
 5. The device of claim 1, wherein the lightsource comprises a laser.
 6. The device of claim 5, wherein the laser isa vertical cavity surface-emissive laser.
 7. The device of claim 5,wherein the optical element is formed on the light-emissive surface ofthe laser.
 8. The device of claim 1, wherein the device is ahead-mounted device, and the device is configured to illuminate an eyeof a user when the user is wearing the head-mounted device.
 9. Thedevice of claim 8, wherein the device further comprises a light sensorconfigured to detect a reflection of the light beam from the eye. 10.The device of claim 8, wherein the device is an augmented reality deviceor a virtual reality device.
 11. The device of claim 1, wherein theoptical element comprises a metamaterial layer.
 12. The device of claim11, wherein the metamaterial layer comprises an arrangement ofnanostructures.
 13. The device of claim 12, wherein the nanostructureseach have a nanostructure parameter, wherein the nanostructure parameterhas a spatial variation as a function of position within themetamaterial layer, the spatial variation being configured to improveillumination uniformity of a target illuminated by the light beam. 14.The device of claim 13, wherein the nanostructure parameter includes atleast one of: a lateral dimension, a cross-sectional area, a lengthdimension, a composition, a nanostructure spacing, a cross-sectionalshape, a cross-sectional shape anisotropy, a cross-sectional uniformity,a taper, a refractive index, a refractive index anisotropy, a coatingthickness, a hollow core thickness, a volume fraction of at least onecomponent, or an orientation.
 15. The device of claim 13, wherein thenanostructures comprise nanopillars, and the nanostructure parameter isa nanopillar diameter.
 16. The device of claim 13, wherein thenanostructures comprise polarization-sensitive nanostructures.
 17. Amethod, comprising: fabricating a laser having an emissive surface;forming a layer on the emissive surface of the laser; forming a resistlayer on the layer, the resist layer having a shape determined by aspatially non-uniform thickness of the resist layer; and etching theshape of the resist layer into the layer to form an optical elementhaving a shaped exit surface, wherein the optical element is supportedby the emissive surface of the laser, receives light from the laser, andis configured to redirect the light by refraction through the shapedexit surface to illuminate a remote target.
 18. The method of claim 17,wherein the shaped exit surface is an oblique surface, and the opticalelement comprises a prism.
 19. The method of claim 17, wherein theshaped exit surface includes a curved exit surface.
 20. The method ofclaim 17, wherein forming the layer on the emissive surface of the lasercomprises forming a passivation layer on the emissive surface and thenforming the layer on the passivation layer.